IP Address Definition and Meaning: What is an IP Address?

IP Address Definition

Also known as an "IP number" or simply an "IP," this is a code made up of numbers separated by three dots that identifies a particular computer on the Internet. Every computer, whether it be a Web server or the computer you're using right now, requires an IP address to connect to the Internet. IP addresses consist of four sets of numbers from 0 to 255, separated by three dots. For example "" or "". Your Internet Service Provider (ISP), will assign you either a static IP address (which is always the same) or a dynamic IP address, (which changes everytime you log on). ISPs typically assign dial-up users a dynamic IP address each time they sign on because it reduces the number of IP addresses they must register. However, if you connect to the Internet through a network or broadband connection, it is more likely that you have a static IP address.

An IP address can be private - for use on a local area network (LAN) - or public - for use on the Internet or other wide area network (WAN). IP addresses can be determined statically - assigned to a computer by a system administrator - or dynamically - assigned by another device on the network on demand.

Every machine on a network has a unique identifier. Just as you would address a letter to send in the mail, computers use the unique identifier to send data to specific computers on a network. Most networks today, including all computers on the Internet, use the TCP/IP protocol as the standard for how to communicate on the network. In the TCP/IP protocol, the unique identifier for a computer is called its IP address.

There are two standards for IP addresses: IP Version 4 (IPv4) and IP Version 6 (IPv6). All computers with IP addresses have an IPv4 address, and many are starting to use the new IPv6 address system as well. Here's what these two address types mean:

IPv4 uses 32 binary bits to create a single unique address on the network. An IPv4 address is expressed by four numbers separated by dots. Each number is the decimal (base-10) representation for an eight-digit binary (base-2) number, also called an octet. For example:

IPv6 uses 128 binary bits to create a single unique address on the network. An IPv6 address is expressed by eight groups of hexadecimal (base-16) numbers separated by colons, as in 2001:cdba:0000:0000:0000:0000:3257:9652. Groups of numbers that contain all zeros are often omitted to save space, leaving a colon separator to mark the gap (as in 2001:cdba::3257:9652).

At the dawn of IPv4 addressing, the Internet was not the large commercial sensation it is today, and most networks were private and closed off from other networks around the world. When the Internet exploded, having only 32 bits to identify a unique Internet address caused people to panic that we'd run out of IP addresses. Under IPv4, there are 232 possible combinations, which offers just under 4.3 billion unique addresses. IPv6 raised that to a panic-relieving 2128 possible addresses. Later, we'll take a closer look at how to understand your computer's IPv4 or IPv6 addresses.

How does your computer get its IP address? An IP address can be either dynamic or static. A static address is one that you configure yourself by editing your computer's network settings. This type of address is rare, and it can create network issues if you use it without a good understanding of TCP/IP. Dynamic addresses are the most common. They're assigned by the Dynamic Host Configuration Protocol (DHCP), a service running on the network. DHCP typically runs on network hardware such as routers or dedicated DHCP servers.

Dynamic IP addresses are issued using a leasing system, meaning that the IP address is only active for a limited time. If the lease expires, the computer will automatically request a new lease. Sometimes, this means the computer will get a new IP address, too, especially if the computer was unplugged from the network between leases. This process is usually transparent to the user unless the computer warns about an IP address conflict on the network (two computers with the same IP address). An address conflict is rare, and today's technology typically fixes the problem automatically.

What is an IP address?

Every device connected to the public Internet is assigned a unique number known as an Internet Protocol (IP) address. IP addresses consist of four numbers separated by periods (also called a 'dotted-quad') and look something like

Since these numbers are usually assigned to internet service providers within region-based blocks, an IP address can often be used to identify the region or country from which a computer is connecting to the Internet. An IP address can sometimes be used to show the user's general location.

Because the numbers may be tedious to deal with, an IP address may also be assigned to a Host name, which is sometimes easier to remember. Hostnames may be looked up to find IP addresses, and vice-versa. At one time ISPs issued one IP address to each user. These are called static IP addresses. Because there is a limited number of IP addresses and with increased usage of the internet ISPs now issue IP addresses in a dynamic fashion out of a pool of IP addresses (Using DHCP). These are referred to as dynamic IP addresses. This also limits the ability of the user to host websites, mail servers, ftp servers, etc. In addition to users connecting to the internet, with virtual hosting, a single machine can act like multiple machines (with multiple domain names and IP addresses).

What Is My IP Address?

In simple terms, IP which stands for Internet Protocol is the method with which two computers are connected via internet and the IP address is the unique code which is used to identify your internet connection and network.

What Are The Details That Form My IP Address?

An IP Address normally has all the information about the user and the internet connection he or she uses. Primarily it contains the information about the internet connection’s server, the proxy servers if any, the location of the servers, the country, city and zip code where the user or the internet connection is registered and the details of the Internet Service Provider.

It is also possible to find out the exact longitude and latitude of the geographical location of a certain IP address.

Why Is It Important To Know My IP Address?

It is almost imperative that you know every detail about everything that you use or connect with. The reason is similar to why you use some antivirus software. The antivirus software is responsible to let you know and block the site that can be potentially harmful for your computer and personal data stored on the system. Knowing your IP address will keep you informed about the slightest of details about your internet connection.

Also, the exercises through which you can find out your IP address, in the same manner you can check out someone else’s IP address and further details. This is very important for companies, professionals and even individuals. The online world is susceptible to numerous hazards including hacking, theft, frauds and is subject to various misuses.

Suppose you are doing business with someone on a remote offsite system. In today’s globalised world in most cases you do not know who you are talking or chatting to on the other end of the internet connection hence there are virtually no means to determine the genuineness of the individual or about what he says or does. Checking out his IP address may help you to find out if some of the basic information about him is in sync with what you have been supplied with.

Let us take an example to establish the same. A man you are about to do business with says that he is based in Philippines and you are based in Ohio. You can run a check on his IP address to find out if he actually is based in Manila or elsewhere in Philippines and that would at least ensure that he has been true about the basics (however, it is always possible that the person is using a proxy program, which essentially means that he is hiding his real IP location by means of another IP address located at another country or town).

Checking IP addresses and finding out server information is more important for organizations that run real time websites and those who are in ecommerce business. Keeping a track of IP addresses is one way how websites determine unique visitors that is important for organizations that run advertisements and different programs on the site.

In the most widely installed level of the Internet Protocol (IP) today, an IP address is a 32-bit number that identifies each sender or receiver of information that is sent in packets across the Internet. When you request an HTML page or send e-mail, the Internet Protocol part of TCP/IP includes your IP address in the message (actually, in each of the packets if more than one is required) and sends it to the IP address that is obtained by looking up the domain name in the Uniform Resource Locator you requested or in the e-mail address you're sending a note to. At the other end, the recipient can see the IP address of the Web page requestor or the e-mail sender and can respond by sending another message using the IP address it received.

An IP address has two parts: the identifier of a particular network on the Internet and an identifier of the particular device (which can be a server or a workstation) within that network. On the Internet itself - that is, between the router that move packets from one point to another along the route - only the network part of the address is looked at.

The Network Part of the IP Address

The Internet is really the interconnection of many individual networks (it's sometimes referred to as an internetwork). So the Internet Protocol (IP) is basically the set of rules for one network communicating with any other (or occasionally, for broadcast messages, all other networks). Each network must know its own address on the Internet and that of any other networks with which it communicates. To be part of the Internet, an organization needs an Internet network number, which it can request from the Network Information Center (NIC). This unique network number is included in any packet sent out of the network onto the Internet.

The Local or Host Part of the IP Address

In addition to the network address or number, information is needed about which specific machine or host in a network is sending or receiving a message. So the IP address needs both the unique network number and a host number (which is unique within the network). (The host number is sometimes called a local or machine address.)

Part of the local address can identify a subnetwork or subnet address, which makes it easier for a network that is divided into several physical subnetworks (for examples, several different local area networks or ) to handle many devices.

IP Address Classes and Their Formats

Since networks vary in size, there are four different address formats or classes to consider when applying to NIC for a network number:

  • Class A addresses are for large networks with many devices.

  • Class B addresses are for medium-sized networks.

  • Class C addresses are for small networks (fewer than 256 devices).

  • Class D addresses are multicast addresses.

The first few bits of each IP address indicate which of the address class formats it is using. The address structures look like this:

Class A


Network (7 bits)

Local address (24 bits)

Class B


Network (14 bits)

Local address (16 bits)

Class C


Network (21 bits)

Local address (8 bits)

Class D


Multicast address (28 bits)

The IP address is usually expressed as four decimal numbers, each representing eight bits, separated by periods. This is sometimes known as the dot address and, more technically, as dotted quad notation. For Class A IP addresses, the numbers would represent "network.local.local.local"; for a Class C IP address, they would represent "network.network.network.local". The number version of the IP address can (and usually is) represented by a name or series of names called the domain name.

The Internet's explosive growth makes it likely that, without some new architecture, the number of possible network addresses using the scheme above would soon be used up (at least, for Class C network addresses). However, a new IP version, IPv6, expands the size of the IP address to 128 bits, which will accommodate a large growth in the number of network addresses. For hosts still using IPv4, the use of subnets in the host or local part of the IP address will help reduce new applications for network numbers. In addition, most sites on today's mostly IPv4 Internet have gotten around the Class C network address limitation by using the Classless Inter-Domain Routing (CIDR) scheme for address notation.

Relationship of the IP Address to the Physical Address

The machine or physical address used within an organization's local area networks may be different than the Internet's IP address. The most typical example is the 48-bit Ethernet address. TCP/IP includes a facility called the Address Resolution Protocol (ARP) that lets the administrator create a table that maps IP addresses to physical addresses. The table is known as the ARP cache.

Static versus Dynamic IP Addresses

The discussion above assumes that IP addresses are assigned on a static basis. In fact, many IP addresses are assigned dynamically from a pool. Many corporate networks and online services economize on the number of IP addresses they use by sharing a pool of IP addresses among a large number of users. If you're an America Online user, for example, your IP address will vary from one logon session to the next because AOL is assigning it to you from a pool that is much smaller than AOL's base of subscribers.

IP address

IP addresses or Internet Protocol addresses are the way in which computers on a network both communicate with each other and know where they all are in relation to one another. An IP address is something like a mailing address for computers on the Internet. This mailing address allows your email to arrive at the right place and your Web page customers to see the correct Web site.

Most IPv4 addresses are in the format:


Each set is a number from 0 to 255. So a typical IP address will look something like this:

If your computer is on an isolated network (meaning, it's not connected to the Internet), it can be assigned any IP address you would like as long as that number is unique on your network. But as soon as that computer is connected to the Internet it needs to be given a registered IP address (which is generally called an Internet address).

Dynamic IPs

Most ISPs grant what are called dynamic IPs to customers connecting to their network. This means that every time you connect to your ISP you're given a different IP address. It is very difficult if not impossible to host a Web page domain on a dynamic IP connection. As every time you connect your server to the Internet the IP address may change. While it is possible to set up a Web server using a dynamic IP ISP, most service providers frown on this. There is usually a clause stating that you cannot use servers on the account.

Static IPs

When you put up a Web page, the server hosting it has to have what is called a static IP. This is an IP address that doesn't change when you login. Thus, if you're going to host your Web server yourself, you need to get an account with a static IP. Generally these are considered "business" accounts and usually cost slightly more than a dynamic IP account, or they are slower than a similarly priced dynamic IP account.

IP and DNS

The IP address is what your domain name is attached to. While one IP address can host numerous domains using DNS aliasing, each domain needs a specific IP address in order to function. When you buy a domain name, you will be asked for the nameservice that will define the IP. However, if you don't have an IP address attached to a computer, most domain name registrars will host your DNS for you - for a price. You can then redirect that domain to your Web site hosted on an ISP or free hosting server or wherever.


Unique 32-bit long code number which each computer acquires automatically through its internet access provider (IAP) for connecting to the internet. This address is in 'a.b.c.d' format where each letter (separated by a period) is a number with value from 0 to 255. However, every computer connected to the internet also has a domain name (consisting of a maximum of 20 alphanumeric characters) which is easier to remember than its associated IP address. Specialized computers (called 'domain name servers' translate the domain names into their corresponding IP addresses so that the recipient (target) computers can be located and the data is correctly routed. Also called web address. See also uniform resource locator.

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