ip address block assignment

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How are IP addresses assigned?

How are IP addresses assigned? What if someone from USA and someone from Australia connected to the internet at the same time - how would they not have the same IP address?

• 1 Why is this computer software/hardware related? because, if you mess up with your IP address, you cannot reach Superuser in the first place -- even, to attempt the other questions you might have to post/answer there ;-) –  nik Commented Jun 12, 2010 at 10:58

3 Answers 3

Because public IP addresses are not picked at random, they are allocated by your Internet Service Provider ; who in-turn gets a block assigned to them from the next level, and so on to IANA/ICANN . Think of this as, only ICANN give IP addresses YOU cannot :-) In your home or college network usually you would use private IP addresses, and might have statically assigned IPs or let your home router do a private IP allocation. These are not visible (or routed) on the Internet. You will find many people use the IP address 192.168.1.1 at their homes, for example, and yet there is apparently no conflict. This is because their home router 'translates' (very crude use of that word here) to the ISP allocated address -- which is what others on the Internet will see.

You might think of this private IP address as a local reference (like, take that left on the next block to reach the cake shop?) for your home router to find your machine in the home network.

If you tried to use a 'public' IP address at random, the ISP will not accept it and you will see no network connectivity.

Update: If you want to dig deeper on why an ISP might want to check what source IP you are using, read through the interaction in comments here... Or, head straight to Wikipedia Smurf Attack .

In the late 1990s, many IP networks would participate in Smurf attacks (that is, they would respond to pings to broadcast addresses). Today, thanks largely to the ease with which administrators can make a network immune to this abuse, very few networks remain vulnerable to Smurf attacks.

The fix is two-fold: Configure individual hosts and routers not to respond to ping requests or broadcasts. Configure routers not to forward packets directed to broadcast addresses. Until 1999, standards required routers to forward such packets by default, but in that year, the standard was changed to require the default to be not to forward. 3

Another proposed solution, to fix this as well as other problems, is network ingress filtering which rejects the attacking packets on the basis of the forged source address .

Thanks to Andy for making me recall this. You might also be interested in in this ServerFault question by Jeff: Are IP addresses “trivial to forge” ?

• If you try to use a public IP address at random, regardless of anything else, any return packets will end up on the wrong network at the wrong host, so you won't be able to have two-way comms. –  Andy Commented Jun 12, 2010 at 11:11
• @Andy, actually the transmitted packets are likely to get dropped themselves. The point is, you cannot convince the ISP network devices to use your choice of IP address. They will not accept it. –  nik Commented Jun 12, 2010 at 11:47
• @nik Totally! I focus on the return path because for me, whether or not your outgoing packet is dropped is a detail (maybe it will, maybe it won't); the fundamental reason you can't use an arbitrary IP address is that you break the routing system, which shows up on the return journey. –  Andy Commented Jun 12, 2010 at 12:07
• @Andy, Umm, the packet with this 'spoofed' source IP will be dropped -- So, analysis of return path is really just theoretical musing. Look at the ifconfig (or ipconfig on Windows) output of your Internet connected machine. You will see two more things associated with your IP address: a subnet mask and a default gateway ip address. Think about what you will setup as the default gateway if you were to change your IP address say from ' a.x.y.z ' to ' b.x.y.z '. Changing it won't work. Now, think further on what that gateway machine will do to your changed-source-IP packet... –  nik Commented Jun 12, 2010 at 12:45
• @Nik Don't see the problem. Sure if you spoof as a.b.c.d/24 and access a.b.c.d+1/24 you'll have problems. But as long as the dest appears to be in a different subnet, the default gateway'll be used, and once we're at routers, only the dest addr is used no? (I don't get your problem with the gateway machine.) We can modify our subnet mask to make (nearly) all addresses appear to be on a different subnet. Or just configure our host to send all packets to the default gateway. That's why I feel it's details - it's absolutely impossible for the return packets to find you. Have I missed something? –  Andy Commented Jun 12, 2010 at 14:19

The assignment of addresses is managed in a hierarchal fashion. At the top of the chain is

Internet Assigned Numbers Authority

They are responsible for the global pool from which they allocate blocks to the

Regional Internet Registries

who are responsible for specific regions of the world. They in turn, allocate from their blocks, to the

Local Internet Registries

or if you prefer Internet Service providers.

Because of the way the address blocks are allocated every global Internet address is unique.

IP addresses are assigned by ICANN, so that won't happen. But there's also a more fundamental reason. IP addresses are used for routing. When a packet comes into a router, it compares the IP address against entries in its routing table, and sends the packet on through the appropriate outgoing line. So IP addresses aren't just arbitrary numbers that are assigned - they are meaningful addresses.

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A Short Guide to IP Addressing

How are ip addresses managed and distributed.

IP addresses are managed by the Internet Assigned Numbers Authority (IANA), which has overall responsibility for the Internet Protocol (IP) address pool, and by the Regional Internet Registries (RIRs) to which IANA distributes large blocks of addresses.

The RIRs manage, distribute, and publicly register IP addresses and related Internet number resources, such as Autonomous System Numbers (ASN) and reverse Domain Name System (DNS ) delegations within their respective regions. They do this according to policies which are developed within their respective regional communities, through open and bottom-up processes.

There are currently five RIRs:

• AfriNIC  – African region
• APNIC  – Asia Pacific region
• ARIN  – North America and several Caribbean and North Atlantic islands
• LACNIC  – Latin America and the Caribbean
• RIPE NCC  – Europe, the Middle East, and parts of Central Asia

The five RIRs together also form the Number Resource Organization (NRO), which carries out joint activities of the RIRs, including joint technical projects, liaison activities, and policy co-ordination. For more background on IP address management visit:

• IANA’s Overview of IP Address Services
• Development of the Regional Internet Registry System , an article published in Cisco’s  Internet Protocol Journal

How are IPv6 addresses allocated?

Both IPv4 and IPv6 addresses are allocated to those who show that they need addresses for their networks.

Shouldn’t addresses be allocated on a geographical basis to ensure that distribution is equitable?

For technical reasons the allocation of IP addresses has to follow the topology of the  network  and not geography or national borders.

Therefore, the addresses are allocated for use in specific networks, as they are required. RIRs allocate IP addresses  using community-developed policies that are designed to ensure that distribution is fair and equitable.

In the early days of the Internet, the method for distributing IP addresses was less formal, resulting in some organisations receiving disproportionately large address ranges.

The RIRs were formed to provide a better way of distributing addresses. They have been successful at developing fair and equitable distribution policies. They have also helped to provide stability of the address pool and routing tables throughout a long period of rapid growth.

What happens when IPv4 addresses run out?

The Internet, in its current form, already has. According to the Number Resource Organization,  the world officially ran out of IPv4 addresses in February 2011 .

The only option now is to divide the allocated properties into smaller portions or to start trading what’s already been assigned – both moves could complicate and compromise your privacy.

Did you find this resource helpful? By donating any amount, you help fund more research and content like this.

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Understanding IP Addressing and CIDR Charts

Every device connected to the Internet needs to have an identifier. Internet Protocol (IP) addresses are the numerical addresses used to identify a particular piece of hardware connected to the Internet.

The two most common versions of IP in use today are Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6). Both IPv4 and IPv6 addresses come from finite pools of numbers.

For IPv4, this pool is 32-bits (2 32 ) in size and contains 4,294,967,296 IPv4 addresses. The IPv6 address space is 128-bits (2 128 ) in size, containing 340,282,366,920,938,463,463,374,607,431,768,211,456 IPv6 addresses.

A bit is a digit in the binary numeral system, the basic unit for storing information.

Not every IP address in the IPv4 or IPv6 pool can be assigned to the machines and devices used to access the Internet. Some IP addresses have been reserved for other uses, such as for use in private networks. This means that the total number of IP addresses available for allocation is less than the total number in the pool.

Network prefixes

IP addresses can be taken from the IPv4 or the IPv6 pool and are divided into two parts, a network section and a host section. The network section identifies the particular network and the host section identifies the particular node (for example, a certain computer) on the Local Area Network (LAN).

IP addresses are assigned to networks in different sized ‘blocks'. The size of the ‘block' assigned is written after an oblique (/), which shows the number of IP addresses contained in that block. For example, if an Internet Service Provider (ISP) is assigned a “/16”, they receive around 64,000 IPv4 addresses. A “/26” network provides 64 IPv4 addresses. The lower the number after the oblique, the more addresses contained in that “block”.

The size of the prefix, in bits, is written after the oblique. This is called “slash notation”. There is a total of 32 bits in IPv4 address space. For example, if a network has the address “192.0.2.0/24”, the number “24” refers to how many bits are contained in the network. From this, the number of bits left for address space can be calculated. As all IPv4 networks have 32 bits, and each “section” of the address denoted by the decimal points contains eight bits, “192.0.2.0/24” leaves eight bits to contain host addresses. This is enough space for 256 host addresses. These host addresses are the IP addresses that are necessary to connect your machine to the Internet.

A network numbered “10.0.0.0/8” (which is one of those reserved for private use) is a network with eight bits of network prefix, denoted by “/8” after the oblique. The “8” denotes that there are 24 bits left over in the network to contain IPv4 host addresses: 16,777,216 addresses to be exact.

Classless Inter-Domain Routing (CIDR) Chart

The Classless Inter-Domain Routing (CIDR) is commonly known as the CIDR chart and is used by those running networks and managing IP addresses. It enables them to see the number of IP addresses contained within each “slash notation” and the size of each “slash notation” in bits.

Download: IPv4 CIDR Chart (PDF)

IPv6 is similar to IPv4, but it is structured so that all LANs have 64 bits of network prefix as opposed to the variable length of network prefix (RFC2526, Reserved IPv6 Subnet Anycast Addresses (Proposed Standard)) that IPv4 networks have. All IPv6 networks have space for 18,446,744,073,709,551,616 IPv6 addresses.

Download: IPv6 Chart (PDF)

Currently, most ISPs assign /48 network prefixes to subscribers' sites (the End Users' networks). Because all IPv6 networks have /64 prefixes, a /48 network prefix allows 65,536 LANs in an End User's site.

The current minimum IPv6 allocation made by the RIPE NCC is a /32 network prefix. If the LIR only made /48 assignments from this /32 network prefix, they would be able to make 65,536 /48 assignments. If they decided to only assign /56 network prefixes they would have 24 bits available to them, and so could make 16,777,216 /56 assignments.

For example, if a /24 IPv6 allocation is made to an LIR, it would be able to make 16,777,216 /48 assignments or 4,294,967,296 /56 assignments.

To give some perspective, it is worth noting that there are 4,294,967,296 IPv4 addresses in total, significantly less than the number of IPv6 addresses.

IPv6 Relative Network Sizes

Understanding IP Address Assignment: A Complete Guide

Introduction

In today's interconnected world, where almost every aspect of our lives relies on the internet, understanding IP address assignment is crucial for ensuring online security and efficient network management. An IP address serves as a unique identifier for devices connected to a network, allowing them to communicate with each other and access the vast resources available on the internet. Whether you're a technical professional, a network administrator, or simply an internet user, having a solid grasp of how IP addresses are assigned within the same network can greatly enhance your ability to troubleshoot connectivity issues and protect your data.

The Basics of IP Addresses

Before delving into the intricacies of IP address assignment in the same network, it's important to have a basic understanding of what an IP address is. In simple terms, an IP address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. It consists of four sets of numbers separated by periods (e.g., 192.168.0.1) and can be either IPv4 or IPv6 format.

IP Address Allocation Methods

There are several methods used for allocating IP addresses within a network. One commonly used method is Dynamic Host Configuration Protocol (DHCP). DHCP allows devices to obtain an IP address automatically from a central server, simplifying the process of managing large networks. Another method is static IP address assignment, where an administrator manually assigns specific addresses to devices within the network. This method provides more control but requires careful planning and documentation.

Considerations for Efficient IP Address Allocation

Efficient allocation of IP addresses is essential for optimizing network performance and avoiding conflicts. When assigning IP addresses, administrators need to consider factors such as subnetting, addressing schemes, and future scalability requirements. By carefully planning the allocation process and implementing best practices such as using private IP ranges and avoiding overlapping subnets, administrators can ensure smooth operation of their networks without running out of available addresses.

IP Address Assignment in the Same Network

When two routers are connected within the same network, they need to obtain unique IP addresses to communicate effectively. This can be achieved through various methods, such as using different subnets or configuring one router as a DHCP server and the other as a client. Understanding how IP address assignment works in this scenario is crucial for maintaining proper network functionality and avoiding conflicts.

Basics of IP Addresses

IP addresses are a fundamental aspect of computer networking that allows devices to communicate with each other over the internet. An IP address, short for Internet Protocol address, is a unique numerical label assigned to each device connected to a network. It serves as an identifier for both the source and destination of data packets transmitted across the network.

The structure of an IP address consists of four sets of numbers separated by periods (e.g., 192.168.0.1). Each set can range from 0 to 255, resulting in a total of approximately 4.3 billion possible unique combinations for IPv4 addresses. However, with the increasing number of devices connected to the internet, IPv6 addresses were introduced to provide a significantly larger pool of available addresses.

IPv4 addresses are still predominantly used today and are divided into different classes based on their range and purpose. Class A addresses have the first octet reserved for network identification, allowing for a large number of hosts within each network. Class B addresses reserve the first two octets for network identification and provide a balance between network size and number of hosts per network. Class C addresses allocate the first three octets for network identification and are commonly used in small networks.

With the depletion of available IPv4 addresses, IPv6 was developed to overcome this limitation by utilizing 128-bit addressing scheme, providing an enormous pool of potential IP addresses - approximately 3.4 x 10^38 unique combinations.

IPv6 addresses are represented in hexadecimal format separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). The longer length allows for more efficient routing and eliminates the need for Network Address Translation (NAT) due to its vast address space.

Understanding these basics is essential when it comes to assigning IP addresses in a network. Network administrators must consider various factors such as the number of devices, network topology, and security requirements when deciding on the IP address allocation method.

In the next section, we will explore different methods of IP address assignment, including Dynamic Host Configuration Protocol (DHCP) and static IP address assignment. These methods play a crucial role in efficiently managing IP addresses within a network and ensuring seamless communication between devices.

Methods of IP Address Assignment

IP address assignment is a crucial aspect of network management and plays a vital role in ensuring seamless connectivity and efficient data transfer. There are primarily two methods of assigning IP addresses in a network: dynamic IP address assignment using the Dynamic Host Configuration Protocol (DHCP) and static IP address assignment.

Dynamic IP Address Assignment using DHCP

Dynamic IP address assignment is the most commonly used method in modern networks. It involves the use of DHCP servers, which dynamically allocate IP addresses to devices on the network. When a device connects to the network, it sends a DHCP request to the DHCP server, which responds by assigning an available IP address from its pool.

One of the key benefits of dynamic IP address assignment is its simplicity and scalability. With dynamic allocation, network administrators don't have to manually configure each device's IP address. Instead, they can rely on the DHCP server to handle this task automatically. This significantly reduces administrative overhead and makes it easier to manage large networks with numerous devices.

Another advantage of dynamic allocation is that it allows for efficient utilization of available IP addresses. Since addresses are assigned on-demand, there is no wastage of unused addresses. This is particularly beneficial in scenarios where devices frequently connect and disconnect from the network, such as in public Wi-Fi hotspots or corporate environments with a high turnover rate.

However, dynamic allocation does have some drawbacks as well. One potential issue is that devices may receive different IP addresses each time they connect to the network. While this might not be an issue for most users, it can cause problems for certain applications or services that rely on consistent addressing.

Additionally, dynamic allocation introduces a dependency on the DHCP server. If the server goes down or becomes unreachable, devices will not be able to obtain an IP address and will be unable to connect to the network. To mitigate this risk, redundant DHCP servers can be deployed for high availability.

Static IP Address Assignment

Static IP address assignment involves manually configuring each device's IP address within the network. Unlike dynamic allocation, where addresses are assigned on-demand, static assignment requires administrators to assign a specific IP address to each device.

One of the main advantages of static IP address assignment is stability. Since devices have fixed addresses, there is no risk of them receiving different addresses each time they connect to the network. This can be beneficial for applications or services that require consistent addressing, such as servers hosting websites or databases.

Static assignment also provides greater control over network resources. Administrators can allocate specific IP addresses to devices based on their requirements or security considerations. For example, critical servers or network infrastructure devices can be assigned static addresses to ensure their availability and ease of management.

However, static IP address assignment has its limitations as well. It can be time-consuming and error-prone, especially in large networks with numerous devices. Any changes to the network topology or addition/removal of devices may require manual reconfiguration of IP addresses, which can be a tedious task.

Furthermore, static allocation can lead to inefficient utilization of available IP addresses. Each device is assigned a fixed address regardless of whether it is actively using the network or not. This can result in wastage of unused addresses and may pose challenges in scenarios where addressing space is limited.

In order to efficiently allocate IP addresses within a network, there are several important considerations that need to be taken into account. By carefully planning and managing the allocation process, network administrators can optimize their IP address usage and ensure smooth operation of their network.

One of the key factors to consider when assigning IP addresses is the size of the network. The number of devices that will be connected to the network determines the range of IP addresses that will be required. It is essential to accurately estimate the number of devices that will need an IP address in order to avoid running out of available addresses or wasting them unnecessarily.

Another consideration is the type of devices that will be connected to the network. Different devices have different requirements in terms of IP address assignment. For example, servers and other critical infrastructure typically require static IP addresses for stability and ease of access. On the other hand, client devices such as laptops and smartphones can often use dynamic IP addresses assigned by a DHCP server.

The physical layout of the network is also an important factor to consider. In larger networks with multiple subnets or VLANs, it may be necessary to segment IP address ranges accordingly. This allows for better organization and management of IP addresses, making it easier to troubleshoot issues and implement security measures.

Security is another crucial consideration when allocating IP addresses. Network administrators should implement measures such as firewalls and intrusion detection systems to protect against unauthorized access or malicious activities. Additionally, assigning unique IP addresses to each device enables better tracking and monitoring, facilitating quick identification and response in case of any security incidents.

Efficient utilization of IP address ranges can also be achieved through proper documentation and record-keeping. Maintaining an up-to-date inventory of all assigned IP addresses helps prevent conflicts or duplicate assignments. It also aids in identifying unused or underutilized portions of the address space, allowing for more efficient allocation in the future.

Furthermore, considering future growth and scalability is essential when allocating IP addresses. Network administrators should plan for potential expansion and allocate IP address ranges accordingly. This foresight ensures that there will be sufficient addresses available to accommodate new devices or additional network segments without disrupting the existing infrastructure.

In any network, the assignment of IP addresses is a crucial aspect that allows devices to communicate with each other effectively. When it comes to IP address assignment in the same network, there are specific considerations and methods to ensure efficient allocation. In this section, we will delve into how two routers in the same network obtain IP addresses and discuss subnetting and IP address range distribution.

To understand how two routers in the same network obtain IP addresses, it's essential to grasp the concept of subnetting. Subnetting involves dividing a larger network into smaller subnetworks or subnets. Each subnet has its own unique range of IP addresses that can be assigned to devices within that particular subnet. This division helps manage and organize large networks efficiently.

When it comes to assigning IP addresses within a subnet, there are various methods available. One common method is manual or static IP address assignment. In this approach, network administrators manually assign a specific IP address to each device within the network. Static IP addresses are typically used for devices that require consistent connectivity and need to be easily identifiable on the network.

Another widely used method for IP address assignment is Dynamic Host Configuration Protocol (DHCP). DHCP is a networking protocol that enables automatic allocation of IP addresses within a network. With DHCP, a server is responsible for assigning IP addresses dynamically as devices connect to the network. This dynamic allocation ensures efficient utilization of available IP addresses by temporarily assigning them to connected devices when needed.

When considering efficient allocation of IP addresses in the same network, several factors come into play. One important consideration is proper planning and design of subnets based on anticipated device count and future growth projections. By carefully analyzing these factors, administrators can allocate appropriate ranges of IP addresses for each subnet, minimizing wastage and ensuring scalability.

Additionally, implementing proper security measures is crucial when assigning IP addresses in the same network. Network administrators should consider implementing firewalls, access control lists (ACLs), and other security mechanisms to protect against unauthorized access and potential IP address conflicts.

Furthermore, monitoring and managing IP address usage is essential for efficient allocation. Regular audits can help identify any unused or underutilized IP addresses that can be reclaimed and allocated to devices as needed. This proactive approach ensures that IP addresses are utilized optimally within the network.

The proper assignment of IP addresses is crucial for maintaining network security and efficiency. Throughout this guide, we have covered the basics of IP addresses, explored different methods of IP address assignment, and discussed considerations for efficient allocation.

In conclusion, understanding IP address assignment in the same network is essential for network administrators and technical professionals. By following proper allocation methods such as DHCP or static IP assignment, organizations can ensure that each device on their network has a unique identifier. This not only enables effective communication and data transfer but also enhances network security by preventing unauthorized access.

Moreover, considering factors like subnetting, scalability, and future growth can help optimize IP address allocation within a network. Network administrators should carefully plan and allocate IP addresses to avoid conflicts or wastage of resources.

Overall, a well-managed IP address assignment process is vital for the smooth functioning of any network. It allows devices to connect seamlessly while ensuring security measures are in place. By adhering to best practices and staying updated with advancements in networking technology, organizations can effectively manage their IP address assignments.

In conclusion, this guide has provided a comprehensive overview of IP address assignment in the same network. We hope it has equipped you with the knowledge needed to make informed decisions regarding your network's IP address allocation. Remember that proper IP address assignment is not only important for connectivity but also plays a significant role in maintaining online security and optimizing network performance.

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ARIN Lookup

About arin lookup.

This test will query the American Registry for Internet Numbers (ARIN) database and tell you who an IP address is registered to. Generally speaking, you will input an IP address and find out what ISP or hosting provider uses that block for its customers. Very large end customers may have there own ARIN allocations. Normally, this is used for finding abuse contacts to report bad behavior.

Subnet Cheat Sheet – 24 Subnet Mask, 30, 26, 27, 29, and other IP Address CIDR Network References

As a developer or network engineer, you may need to occasionally look up subnet mask values and figure out what they mean.

To make your life easier, the freeCodeCamp community has made this simple cheat sheet. Just scroll or use Ctrl/Cmd + f to find the value you're looking for.

Here are the charts, followed by some explanations of what they mean.

• /31 is a special case detailed in RFC 3021 where networks with this type of subnet mask can assign two IP addresses as a point-to-point link.

And here's a table of the decimal to binary conversions for subnet mask and wildcard octets:

Note that the wildcard is just the inverse of the subnet mask.

If you are new to network engineering, you can get a better idea of how computer networks work here .

Finally, this cheat sheet and the rest of the article is focused on IPv4 addresses, not the newer IPv6 protocol. If you'd like to learn more about IPv6, check out the article on computer networks above.

How Do IP Address Blocks Work?

IPv4 addresses like 192.168.0.1 are really just decimal representations of four binary blocks.

Each block is 8 bits, and represents numbers from 0-255. Because the blocks are groups of 8 bits, each block is known as an octet . And since there are four blocks of 8 bits, every IPv4 address is 32 bits.

For example, here's what the IP address 172.16.254.1 looks like in binary:

To convert an IP address between its decimal and binary forms, you can use this chart:

The chart above represents one 8 bit octive.

Now lets say you want to convert the IP address 168.210.225.206 . All you need to do is break the address into four blocks ( 168 , 210 , 225 , and 206 ), and convert each into binary using the chart above.

Remember that in binary, 1 is the equivalent to "on" and 0 is "off". So to convert the first block, 168 , into binary, just start from the beginning of the chart and place a 1 or 0 in that cell until you get a sum of 168 .

For example:

128 + 32 + 8 = 168, which in binary is 10101000 .

If you do this for the rest of the blocks, you'd get 10101000.11010010.11100001.11001110 .

What is Subnetting?

If you look at the table above, it can seem like the number of IP addresses is practically unlimited. After all, there are almost 4.2 billion possible IPv4 addresses available.

But if you think about how much the internet has grown, and how many more devices are connected these days, it might not surprise you to hear that there's already a shortage of IPv4 addresses .

Because the shortage was recognized years ago, developers came up with a way to split up an IP address into smaller networks called subnets.

This process, called subnetting, uses the host section of the IP address to break it down into those smaller networks or subnets.

Generally, an IP address is made up of network bits and host bits:

So generally, subnetting does two things: it gives us a way to break up networks into subnets, and allows devices to determine whether another device/IP address is on the same local network or not.

A good way to think about subnetting is to picture your wireless network at home.

Without subnetting, every internet connected device would need its own unique IP address.

But since you have a wireless router, you just need one IP address for your router. This public or external IP address is usually handled automatically, and is assigned by your internet service provider (ISP).

Then every device connected to that router has its own private or internal IP address:

Now if your device with the internal IP address 192.168.1.101 wants to communicate with another device, it'll use the IP address of the other device and the subnet mask.

The combination of the IP addresses and subnet mask allows the device at 192.168.1.101 to figure out if the other device is on the same network (like the device at 192.168.1.103 ), or on a completely different network somewhere else online.

Interestingly, the external IP address assigned to your router by your ISP is probably part of a subnet, which might include many other IP addresses for nearby homes or businesses. And just like internal IP addresses, it also needs a subnet mask to work.

How Subnet Masks Work

Subnet masks function as a sort of filter for an IP address. With a subnet mask, devices can look at an IP address, and figure out which parts are the network bits and which are the host bits.

Then using those things, it can figure out the best way for those devices to communicate.

If you've poked around the network settings on your router or computer, you've likely seen this number: 255.255.255.0 .

If so, you've seen a very common subnet mask for simple home networks.

Like IPv4 addresses, subnet masks are 32 bits. And just like converting an IP address into binary, you can do the same thing with a subnet mask.

For example, here's our chart from earlier:

Now let's convert the first octet, 255:

Pretty simple, right? So any octet that's 255 is just 11111111 in binary. This means that 255.255.255.0 is really 11111111.11111111.11111111.00000000 in binary.

Now let's look at a subnet mask and IP address together and calculate which parts of the IP address are the network bits and host bits.

Here are the two in both decimal and binary:

With the two laid out like this, it's easy to separate 192.168.0.101 into network bits and host bits.

Whenever a bit in a binary subnet mask is 1, then the same bit in a binary IP address is part of the network, not the host.

Since the octet 255 is 11111111 in binary, that whole octet in the IP address is part of the network. So the first three octets, 192.168.0 , is the network portion of the IP address, and 101 is the host portion.

In other words, if the device at 192.168.0.101 wants to communicate with another device, using the subnet mask it knows that anything with the IP address 192.168.0.xxx is on the same local network.

Another way to express this is with a network ID, which is just the network portion of the IP address. So the network ID of the address 192.168.0.101 with a subnet mask of 255.255.255.0 is 192.168.0.0 .

And it's the same for the other devices on the local network ( 192.168.0.102 , 192.168.0.103 , and so on).

What Does CIDR Mean and What is CIDR Notation?

CIDR stands for Classless Inter-Domain Routing, and is used in IPv4, and more recently, IPv6 routing.

CIDR was introduced in 1993 as a way to slow the usage of IPv4 addresses, which were quickly being exhausted under the older Classful IP addressing system that the internet was first built on.

CIDR encompasses a couple of major concepts.

The first is Variable Length Submasking (VLSM), which basically allowed network engineers to create subnets within subnets. And those subnets could be different sizes, so there would be fewer unused IP addresses.

The second major concept CIDR introduced is CIDR notation.

CIDR notation is really just shorthand for the subnet mask, and represents the number of bits available to the IP address. For instance, the /24 in 192.168.0.101/24 is equivalent to the IP address 192.168.0.101 and the subnet mask 255.255.255.0 .

How to Calculate CIDR Noation

To figure out the CIDR notation for a given subnet mask, all you need to do is convert the subnet mask into binary, then count the number of ones or "on" digits. For example:

Because there's three octets of ones, there are 24 "on" bits meaning that the CIDR notation is /24 .

You can write it either way, but I'm sure you'll agree that /24 is a whole lot easier to write than 255.255.255.0 .

This is usually done with an IP address, so let's take a look at the same subnet mask with an IP address:

The first three octets of the subnet mask are all "on" bits, so that means that the same three octets in the IP address are all network bits.

Let's take a look at the last forth octet in a bit more detail:

In this case, because all the bits for this octet in the subnet mask are "off", we can be certain that all of the corresponding bits for this octet in the IP address are part of the host.

When you write CIDR notation it's usually done with the network ID. So the CIDR notation of the IP address 192.168.0.101 with a subnet mask of 255.255.255.0 is 192.168.0.0/24 .

To see more examples of how to calculate the CIDR notation and network ID for a given IP address and subnet mask, check out this video:

Classful IP Addressing

Now that we've gone over some basic examples of subnetting and CIDR, let's zoom out and look at what's known as Classful IP addressing.

Back before subnetting was developed, all IP addresses fell into a particular class:

Note that there are class D and E IP addresses, but we'll go into these in more detail a bit later.

Classful IP addresses gave network engineers a way to provide different organizations with a range of valid IP addresses.

There were a lot of issues with this approach that eventually lead to subnetting. But before we get into those, let's take a closer look at the different classes.

Class A IP Addresses

For Class A IP addresses, the first octet (8 bits / 1 byte) represent the network ID, and the remaining three octets (24 bits / 3 bytes) are the host ID.

Class A IP addresses range from 1.0.0.0 to 127.255.255.255 , with a default mask of 255.0.0.0 (or /8 in CIDR).

This means that Class A addressing can have a total of 128 (2 7 ) networks and 16,777,214 (2 24 -2) usable addresses per network.

Also, note that the range 127.0.0.0 to 127.255.255.255 within the Class A range is reserved for host loopback address (see RFC5735 ).

Class B IP Addresses

For Class B IP addresses, the first two octets (16 bits / 2 bytes) represent the network ID and the remaining two octets (16 bits / 2 bytes) are the host ID.

Class B IP addresses range from 128.0.0.0 to 191.255.255.255 , with a default subnet mask of 255.255.0.0 (or /16 in CIDR).

Class B addressing can have 16,384 (2 14 ) network addresses and 65,534 (2 16 ) usable addresses per network.

Class C IP Addresses

For Class C IP addresses, the first three octets (24 bits / 3 bytes) represent the network ID and the last octet (8 bits / 1 bytes) is the host ID.

Class C IP Addresses range from 192.0.0.0 to 223.255.255.255 , with a default subnet mask of 255.255.255.0 (or /24 in CIDR).

Class C translates to 2,097,152 (2 21 ) networks and 254 (2 8 -2) usable addresses per network.

Class D and Class E IP Addresses

The last two classes are Class D and Class E.

Class D IP addresses are reserved for multicasts. They occupy the range from 224.0.0.0 through 239.255.255.255 .

Class E IP addresses are experimental, and are anything over 240.0.0.0 .

The Issue with Classful IP Addresses

The main issue with classful IP addresses is that it wasn't efficient, and could lead to a lot of wasted IP addresses.

For example, imagine that you're part of a large organization back then. Your company has 1,000 employees, meaning that it would fall into class B.

But if you look above, you'll see that a class B network can support up to 65,534 usable addresses. That's way more than your organization would likely need, even if each employee had multiple devices with a unique address.

And there was no way your organization could fall back to class C – there just wouldn't be enough usable IP addresses.

So while classful IP addresses were used around the time IPv4 addresses became widespread, it quickly became clear that a better system would be necessary to ensure we wouldn't use up all of the ~4.2 billion usable addresses.

Classful IP addresses haven't been used since they were replaced by CIDR in 1993, and are mostly studied to understand early internet architecture, and why subnetting is important.

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IP Subnet Calculator

This calculator returns a variety of information regarding Internet Protocol version 4 (IPv4) and IPv6 subnets including possible network addresses, usable host ranges, subnet mask, and IP class, among others.

IPv4 Subnet Calculator

IPv6 Subnet Calculator

Related Bandwidth Calculator | Binary Calculator

A subnet is a division of an IP network (internet protocol suite), where an IP network is a set of communications protocols used on the Internet and other similar networks. It is commonly known as TCP/IP (Transmission Control Protocol/Internet Protocol).

The act of dividing a network into at least two separate networks is called subnetting, and routers are devices that allow traffic exchange between subnetworks, serving as a physical boundary. IPv4 is the most common network addressing architecture used, though the use of IPv6 has been growing since 2006.

An IP address is comprised of a network number (routing prefix) and a rest field (host identifier). A rest field is an identifier that is specific to a given host or network interface. A routing prefix is often expressed using Classless Inter-Domain Routing (CIDR) notation for both IPv4 and IPv6. CIDR is a method used to create unique identifiers for networks, as well as individual devices. For IPv4, networks can also be characterized using a subnet mask, which is sometimes expressed in dot-decimal notation, as shown in the "Subnet" field in the calculator. All hosts on a subnetwork have the same network prefix, unlike the host identifier, which is a unique local identification. In IPv4, these subnet masks are used to differentiate the network number and host identifier. In IPv6, the network prefix performs a similar function as the subnet mask in IPv4, with the prefix length representing the number of bits in the address.

Prior to the introduction of CIDR, IPv4 network prefixes could be directly obtained from the IP address based on the class (A, B, or C, which vary based on the range of IP addresses they include) of the address and the network mask. Since the introduction of CIDRs, however, assigning an IP address to a network interface requires both an address and its network mask.

Below is a table providing typical subnets for IPv4.

• Settings Profile and security information

Reporting Reassignments

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Note: ARIN retired its original email template processor on 3 June 2024 . If you are an ARIN customer who relied on templates to manage your registration records, we encourage you to use our Reg-RWS service. You may also utilize our open-source template processor .

The Big Picture

Before using or designing software to manage records within ARIN’s database, it is important to understand ARIN’s relational database, and how ARIN maintains records and interacts with customers.

IP Address and Autonomous System Number (ASN) Distribution

ARIN is one of five Regional Internet Registries (RIRs). RIRs are nonprofit corporations that administer and issue IP address space and ASNs within defined regions . RIRs receive address space in large blocks from the Internet Assigned Numbers Authority (IANA), and allocate smaller address blocks to organizations within their regions. These organizations then assign IP addresses to consumers.

Allocations vs. Assignments

• When ARIN issues a block of IP addresses to a customer planning to issue pieces of that block to its own customers, this is known as an direct allocation or allocation .

When an ARIN customer issues a piece of their allocation to a customer of their own, this is known as a reallocation or reassignment, depending on whether their customer intends to issue pieces of that block to customers of their own (reallocation) or if it is intended for internal use (reassignment).

Note : Reallocations and reassignments may only be made from an allocation.

Autonomous System Numbers (ASNs)

ASNs are assigned individually by ARIN and may not be allocated.

Simple vs. Detailed Reassignments

Simple reassignments are those where the customer does not need to maintain their own in-addr.arpa delegation (reverse name server), display their own Point of Contact information, or divide their address space further among their own customers. A detailed reassignment is one in which the customer does not need to further divide the address space but does need to maintain its own in-addr.arpa delegation and/or display separate Point of Contact information.

Resource Requests

In order for ARIN to properly issue Internet number resources to organizations within its region, those organizations submit a resource request, stating which type of resources they need, and how they intend to use them. ARIN requires that requests include utilization plans, so that ARIN can allocate them fairly among organizations as they continue to expand their networks and customer bases.

Keeping Track of Who Uses What

ARIN maintains a database that contains detailed records of which resources have been allocated and assigned, as well as which organizations and Points of Contact are authoritative over those resource records.

Before You Get Started

Requirements.

When an organization reallocates or reassigns address space, they report reallocation/reassignment information to ARIN. This information is vital, as ARIN makes allocations based on an organization’s utilization history, projected requirements, and other information. While initial allocations may be relatively small, subsequent allocation sizes are scaled based partially on growth shown via reallocation/reassignment information received by ARIN.

ARIN policy requires organizations to submit information for all IPv4 reassignments/reallocations of /29 or more and IPv6 reassignments/reallocations of /47 or more within seven days of the subdelegation. For IPv4 blocks of /30 or less, ISPs may choose to provide utilization data using one of the methods described on this page or manually upon request. There are special reporting requirements for residential cable ISPs and residential customers. Organizations may only submit reassignment data for records within their allocated blocks. ARIN may request reassignment/reallocation information at any time. If the organization does not supply the information, ARIN may withhold future allocations, and in extreme cases, existing allocations may be affected.

Note : Organization Identifiers (Org IDs) containing a -Z are not eligible to receive reallocations/reassignments.

Create an ARIN Online Account

Your first step is to create an ARIN Online account , regardless of the reporting method you intend to use.

Create an API Key

After creating your account and logging in to ARIN Online, you need to create an API key to be able to report reassignment/reallocation information using Registration Restful Service (Reg-RWS). An API key provides a means of secure communication with ARIN.

Create a Point of Contact and Give it Authority

Before reporting reallocation/reassignment data, your ARIN Online account must have the authority to do so. ARIN’s Reg-RWS will not process any modifications to a database record unless you have an ARIN Online account linked to a Point of Contact with proper authority over that record. Visit Creating a Points of Contact for more information.

After you create or find the correct Points of Contact in ARIN’s database, that Point of Contact must be linked to your ARIN Online account. Visit Linking a Point of Contact to Your ARIN Online Account for more information.

Finally, you will need to create or find the appropriate Organization Identifier (Org ID) to add your Point of Contact to it as an Admin and/or Tech Point of Contact. This allows your Point of Contact (and your ARIN Online account) to make changes to ARIN’s database regarding your Org ID and any resources attached to it. Visit Creating an Org ID for more information.

ARIN Customers have three options when it comes to reporting their reallocation/reassignment data: Reg-RWS, Referral Whois (RWhois), and ARIN Online.

Reporting Reallocation/Reassignment Data using Reg-RWS

Reg-RWS is a secure and efficient method for interacting with ARIN’s database and managing your registration records. Reg-RWS is most handy for repetitive, mundane tasks done in high volume with no needed human communication, such as reporting reassignments using the Shared Whois Project (SWIP). Generally, most users of ARIN’s Reg-RWS are engineers who code software that works with the Reg-RWS API to automate large numbers of transactions with the ARIN database. Although Reg-RWS commands can be entered individually into a browser, most users who want to run simple queries or report a few transactions use easier methods such as ARIN Online to do so. More information about this method is available on the Automating Record Management with Reg-RWS page .

Reporting Reallocation/Reassignment Data using RWhois

RWhois is an extension of the original Whois protocol and service. It focuses on the distribution of data representing networks and Points of Contact, and uses the inherently hierarchical nature of these network objects (domain names, IP networks, email addresses) to more accurately discover the requested information. RWhois allows organizations to advertise their reallocation/reassignment from an internal server, rather than actively sending it to ARIN. There are numerous requirements for using this sort of distribution server for reallocation/reassignment information, including 24/7 server functionality, response qualification, and continuity of data. For details, see Section 3.2 of ARIN’s Number Resource Policy Manual (NRPM) . More information about this method is available on the Referral Whois (RWhois) page .

Reporting Reallocation/Reassignment Data using ARIN Online.

Creating reassignments.

To reassign network address space, you have the following options:

Option 1: View free blocks and reassign:

• In ARIN Online, choose IP Addresses > Reassign Addresses from the navigation menu. A list of unassigned address space is displayed. (Note that users with over 11,000 NETS will not see this list. See the note at the end of this section.)
• In the list of networks, choose the network space that you want to reassign.
• Choose the size of the CIDR block to reassign, then choose Reassign .

Option 2: View networks and enter a range to reassign:

• From the Dashboard, under Account Snapshot, choose Networks (NETs) to access the Manage Your Networks page. A list of NETS associated with your account is displayed. (Note that users with over 11,000 NETS will not see a list of associated NETS. See the note at the end of this section.)
• In the list of networks, expand the informational panel for the network portion that you want to reassign by selecting the plus sign located to the right of the Org ID. The actions available to you (depending on permissions and resources) appear under NET Actions .

Tip : Copy the Network Range so that you can easily enter it later in the Reassignment Details screen.

Note for Users With 11,000 or More Associated NETS:

• Choosing IP Addresses > Reassign Addresses will not provide the list of free blocks. You’ll need to enter the IP address in the IP Address Range field in the Reassignment Details page and follow the instructions in the subsequent screens.
• Choosing IP Addresses > Search will not display a list of NETS associated with you. You’ll need to enter an IP address in its entirety and choose Search to display it.

Deleting Reassignments

First, find the network that was reassigned by selecting IP Addresses > Manage Networks from the navigation menu. Search for the reassignment to be deleted. Be sure that you have selected the option to “Include the ### networks you’ve reassigned in your search.”

To delete a reassigned/reallocated NET:

• In the list of search results, expand the informational panel for the NET by selecting the plus sign located to the right of the Org ID.
• Under NET Actions , choose Delete to open the Delete Network page. The page provides information about the reassigned/reallocated space and any additional reassignments contained that were made under the reallocation.
• Choose Delete to remove the NET. Any additional reassignments that were made after the initial reallocation are also removed.

Caution : You can’t undo this deletion.

To remove individual reassignments from a list of reassignments of a space:

• In the list of search results, click the Net Handle to open the Manage Network page for that NET.
• From the Actions button, choose Delete Reassignments . A list of the reassignments is displayed.
• On the Delete Reassignments page, choose an individual network by clicking on the Net Handle .
• On the Manage Network page, choose Delete .

To delete all reassignments under a network:

• From the Actions button, choose Delete Reassignments. A list of the reassignments is displayed.
• Choose Delete All Reassignments .
• Confirm the deletion.

Making Changes to Simple Reassigned Orgs Using ARIN Online

To make changes to simple reassigned Orgs, you have the following options:

• Choose IP Addresses, then Manage Networks from the navigation menu. This page will allow you to search your associated networks.
• In the search field, enter the network that you want to make changes to.
• Check the box ‘Include the ### networks you’ve reassigned in your search’ option and select Search.
• In the search results, select the Net Handle for the network.
• In the Network Information panel select Actions , then Modify will present you with the options to modify your network record; Or, in the Network Information panel, under Actions menu, Modify Customer will present you with the options to modify your customer record.

Note: Updating this information keeps the registered date for the Org unchanged.

• Referral Whois (RWhois)
• Requesting Removal of Stale Reassignment and Reallocation Records
• Open-source Template Processor (TP)
• Detailed Reassignment and Reallocations
• Introduction to ARIN's Database
• Automating Record Management with Reg-RWS

Registration Services Help Desk 7:00 AM to 7:00 PM ET Phone: +1.703.227.0660 Fax: +1.703.997.8844

Tips for Calling the Help Desk

In the IPv4 IP address space, there are five classes: A, B, C, D and E. Each class has a specific range of IP addresses (and ultimately dictates the number of devices you can have on your network). Primarily, class A, B, and C are used by the majority of devices on the Internet. Class D and class E are for special uses.

The list below shows the five available IP classes, along with the number of networks each can support and the maximum number of hosts (devices) that can be on each of those networks. The four octets that make up an IP address are conventionally represented by a.b.c.d - such as 127.10.20.30.

Additionally, information is also provided on private addresses and loop address (used for network troubleshooting).

Class A Public & Private IP Address Range

Class A addresses are for networks with large number of total hosts. Class A allows for 126 networks by using the first octet for the network ID. The first bit in this octet, is always zero. The remaining seven bits in this octet complete the network ID. The 24 bits in the remaining three octets represent the hosts ID and allows for approximately 17 million hosts per network. Class A network number values begin at 1 and end at 127.

• First octet value range from 1 to 127
• Private IP Range: 10.0.0.0 to 10.255.255.255 (See Private IP Addresses below for more information)
• Subnet Mask: 255.0.0.0 (8 bits)
• Number of Networks: 126
• Number of Hosts per Network: 16,777,214

Class B Public & Private IP Address Range

Class B addresses are for medium to large sized networks. Class B allows for 16,384 networks by using the first two octets for the network ID. The first two bits in the first octet are always 1 0. The remaining six bits, together with the second octet, complete the network ID. The 16 bits in the third and fourth octet represent host ID and allows for approximately 65,000 hosts per network. Class B network number values begin at 128 and end at 191.

• First octet value range from 128 to 191
• Private IP Range: 172.16.0.0 to 172.31.255.255 (See Private IP Addresses below for more information)
• Subnet Mask: 255.255.0.0 (16 bits)
• Number of Networks: 16,382
• Number of Hosts per Network: 65,534

Class C Public & Private IP Address Range

Class C addresses are used in small local area networks (LANs). Class C allows for approximately 2 million networks by using the first three octets for the network ID. In a class C IP address, the first three bits of the first octet are always 1 1 0. And the remaining 21 bits of first three octets complete the network ID. The last octet (8 bits) represent the host ID and allows for 254 hosts per network. Class C network number values begins at 192 and end at 223.

• First octet value range from 192 to 223
• Private IP Range: 192.168.0.0 to 192.168.255.255 (See Private IP Addresses below for more information)
• Special IP Range: 127.0.0.1 to 127.255.255.255 (See Special IP Addresses below for more information)
• Subnet Mask: 255.255.255.0 (24 bits)
• Number of Networks: 2,097,150
• Number of Hosts per Network: 254

Class D IP Address Range

Class D IP addresses are not allocated to hosts and are used for multicasting. Multicasting allows a single host to send a single stream of data to thousands of hosts across the Internet at the same time. It is often used for audio and video streaming, such as IP-based cable TV networks. Another example is the delivery of real-time stock market data from one source to many brokerage companies.

• First octet value range from 224 to 239
• Number of Networks: N/A
• Number of Hosts per Network: Multicasting

Class E IP Address Class

Class E IP addresses are not allocated to hosts and are not available for general use. These are reserved for research purposes.

• First octet value range from 240 to 255
• Number of Hosts per Network: Research/Reserved/Experimental

Private IP Addresses

Within each network class, there are designated IP address that is reserved specifically for private/internal use only. This IP address cannot be used on Internet-facing devices as that are non-routable. For example, web servers and FTP servers must use non-private IP addresses. However, within your own home or business network, private IP addresses are assigned to your devices (such as workstations, printers, and file servers).

• Class A Private Range: 10.0.0.0 to 10.255.255.255
• Automatic Private IP Addressing (APIPA) is a feature with Microsoft Windows -based computers to automatically assign itself an IP address within this range if a Dynamic Host Configuration Protocol (DHCP) server is not available on the network. A DHCP server is a network device that is responsible for assigning IP addresses to devices on the network. At your home, your Internet modem or router likely provides this functionality. In your work place, a Microsoft Windows Server , a network firewall, or some other specialized network device likely provides this functionality for the computer at your work environment.
• Class B Private Range: 172.16.0.0 to 172.31.255.255
• Class C Private Range: 192.168.0.0 to 192.168.255.255

Special IP Addresses

• IP Range: 127.0.0.1 to 127.255.255.255 are network testing addresses (also referred to as loop-back addresses). These are virtual IP address, in that they cannot be assigned to a device. Specifically, the IP 127.0.0.1 is often used to troubleshoot network connectivity issues using the ping command . Specifically, it tests a computer's TCP/IP network software driver to ensure it is working properly. Learn how to use ping 127.0.0.1 to test your computer's TCP/IP network stack.

Summary of IPv4 Classes

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IANA IPv4 Special-Purpose Address Registry

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IP Address Details

IP Location: Moscow, Moskva (RU)   [Details]

ISP: LLC Internet Tehnologii

Proxy: Not detected.

Platform: Windows 7

Browser: Firefox 107.0   [User Agent]

Screen Size:

Javascript: Enabled

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Why do you need geolocation?

There are several ways to find the geolocation of a user: HTML5 API, Cell Signal, and IP Address to name a few. The pairing of an IP address to a geographical location is the method we used to provide geolocation data. There are times when you need to identify where your web visitors are coming from. You might have an ecommerce website, and would like to know where your potential customers are, pre-populate country codes on forms, display different languages and reduce credit card fraud based on geographic location. Or, you might want to fight against illegal spammers and hackers and would like to locate the sources of a problem.

Although it would be nice to be able to find the precise location of a visitor, it is almost impossible to find the exact location of a host given its IP address . However, there are tools available to help identify the approximate location of the host. ARIN Whois database provides a mechanism for finding contact and registration information for IP resources registered with ARIN.

You may also use 3rd party websites such as Geobytes or Dnsstuff to look up the IP address. The whois lookup will reveal the name of the ISP who owns that IP address, and the country where it originated from. If you're lucky, you might also find the city of origin. You may also use products developed by 3rd-party companies like Ip2location and MaxMind.

You may also use reverse DNS to find out the hostname of the IP address, which might give you some clues. Many ISPs, Corporations, and Academic institutions use location as a qualified hostname, although this is not always true. A couple of things to note here: (1) Reverse DNS translation do not always work. It depends on the correct configuration of the ISP's DNS server. (2) The US domain names such as .com, .net and .org does not always imply that the host is located in the United States.

You may use ' traceroute ' command to find clues to the location of the IP address. The names of the routers through which packets flow from your host to the destination host might hint at the geographical path of the final location.

IP-based Geolocation FAQ

1. what is ip-based geolocation.

IP-based Geolocation is the mapping of an IP address or MAC address to the real-world geographic location of an Internet-connected computing or a mobile device. Geolocation involves mapping IP addresses to the country, region (city), latitude/longitude, ISP, and domain name among other useful things.

2. Where can I get an IP-based Geolocation database?

There are several commercially available geolocation databases, and their pricing and accuracy may vary. Ip2location, MaxMind, Tamo Soft, DB-IP, Ipinfo, and IPligence offer fee-based databases that can be easily integrated into a web application. Most geolocation database vendors offer APIs and example codes (in ASP, PHP, .NET, and Java programming languages) that can be used to retrieve geolocation data from the database. We use several commercial databases to offer free geolocation data on our website.

There are also freely available geolocation databases. Vendors offering commercial geolocation databases also offer a Lite or Community edition that provides IP-to-Country mappings. Ip2Country.net and Webhosting.info (Directi) offer free IP-to-Country databases that can be also integrated into your web application. There are companies also offering free web services that can be used to show the geolocation of an IP address on your website.

3. How accurate is IP-based Geolocation?

The accuracy of the geolocation database varies depending on which database you use. For IP-to-country databases, some vendors claim to offer 98% to 99% accuracy although typical Ip2Country database accuracy is more like 95%. For IP-to-Region (or City), accuracy range anywhere from 50% to 75% if neighboring cities are treated as correct. Considering that there is no official source of IP-to-Region information, 50+% accuracy is pretty good.

4. How does IP-based geolocation work?

ARIN Whois database provides a mechanism for finding contact and registration information for IP resources registered with ARIN. The IP whois information is available for free, and determining the country from this database is relatively easy. When an organization requires a block of IP addresses, a request is submitted, and allocated IP addresses are assigned to a requested ISP.

Common Network Questions

• Do you want to find an IP address of your network printer? Please read How to find an IP of a printer to find ways to obtain an IP number of your network printer.

• Do you want to find IP Addresses of private network? Please read How to find IP addresses of computing devices on the private network?

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IP Address Articles

March 1, 2016

How to hide my IP address?

There are several ways to hide your IP address, and your geolocation. Hiding your IP address is concealing your "true" IP address with a different one. You may use a VPN, Proxy or Anonymous Browser to hide your IP address.

April 14, 2016

How to change your IP address?

Would you like to change the IP address of your computer, smartphone or tablet? You're getting your IP address from your Internet Service Provider, and you have the right to obtain a new IP address whenever you desire. Let us show you how you can change an IP address of your device.

February 15, 2012

What is the difference between public and private IP address?

A public IP address is an IP address that can be accessed over the Internet, and a private IP address is an IP address that is local to your private network. A public IP is a globally unique IP, while a private IP address can be reused in different networks.

October 7, 2012

What is the difference between a static and dynamic IP address?

An IP address is an address assigned to a device on the Internet. A static IP address is a fixed IP address that never changes, and a dynamic IP address is an IP that is assigned by the DHCP server which may change over time.

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