(Internet Protocol address) The address of a device attached to an IP network (TCP/IP network). Every client, server and network device is assigned an IP address, and every IP packet traversing an IP network contains a source IP address and a destination IP address.
Every IP address that is exposed to the public Internet is unique. In contrast, IP addresses within a local network use the same private addresses; thus, a user's computer in company A can have the same address as a user in company B and thousands of other companies. However, private IP addresses are not reachable from the outside world (see private IP address).
Logical Vs. Physical
An IP address is a logical address that is assigned by software residing in a server or router (see DHCP). In order to locate a device in the network, the logical IP address is converted to a physical address by a function within the TCP/IP protocol software (see ARP). The physical address is actually built into the hardware (see MAC address).
Static and Dynamic IP
Network infrastructure devices such as servers, routers and firewalls are typically assigned permanent "static" IP addresses. The client machines can also be assigned static IPs by a network administrator, but most often are automatically assigned temporary "dynamic" IP addresses via software that uses the "dynamic host configuration protocol" (see DHCP). Cable and DSL modems typically use dynamic IP with a new IP address assigned to the modem each time it is rebooted.
The Dotted Decimal Address: x.x.x.x
IP addresses are written in "dotted decimal" notation, which is four sets of numbers separated by decimal points; for example, 204.171.64.2. Instead of the domain name of a Web site, the actual IP address can be entered into the browser. However, the Domain Name System (DNS) exists so users can enter computerlanguage.com instead of an IP address, and the domain (the URL) computerlanguage.com is converted to the numeric IP address (see DNS).
Although the next version of the IP protocol offers essentially an unlimited number of unique IP addresses (see IPv6), the traditional IP addressing system (IPv4) uses a smaller 32-bit number that is split between the network and host (client, server, etc.). The host part can be further divided into subnetworks (see subnet mask).
Class A, B and C
Based on the split of the 32 bits, an IP address is either Class A, B or C, the most common of which is Class C. More than two million Class C addresses are assigned, quite often in large blocks to network access providers for use by their customers. The fewest are Class A networks, which are reserved for government agencies and huge companies.
Although people identify the class by the first number in the IP address (see table below), a computer identifies class by the first three bits of the IP address (A=0; B=10; C=110). This class system has also been greatly expanded, eliminating the huge disparity in the number of hosts that each class can accommodate (see CIDR). See private IP address and IP.
Networks, Subnets and Hosts
An IP address is first divided between networks and hosts. The host bits are further divided between subnets and hosts. See subnet mask.
Every IP address that is exposed to the public Internet is unique. In contrast, IP addresses within a local network use the same private addresses; thus, a user's computer in company A can have the same address as a user in company B and thousands of other companies. However, private IP addresses are not reachable from the outside world (see private IP address).
Logical Vs. Physical
An IP address is a logical address that is assigned by software residing in a server or router (see DHCP). In order to locate a device in the network, the logical IP address is converted to a physical address by a function within the TCP/IP protocol software (see ARP). The physical address is actually built into the hardware (see MAC address).
Static and Dynamic IP
Network infrastructure devices such as servers, routers and firewalls are typically assigned permanent "static" IP addresses. The client machines can also be assigned static IPs by a network administrator, but most often are automatically assigned temporary "dynamic" IP addresses via software that uses the "dynamic host configuration protocol" (see DHCP). Cable and DSL modems typically use dynamic IP with a new IP address assigned to the modem each time it is rebooted.
The Dotted Decimal Address: x.x.x.x
IP addresses are written in "dotted decimal" notation, which is four sets of numbers separated by decimal points; for example, 204.171.64.2. Instead of the domain name of a Web site, the actual IP address can be entered into the browser. However, the Domain Name System (DNS) exists so users can enter computerlanguage.com instead of an IP address, and the domain (the URL) computerlanguage.com is converted to the numeric IP address (see DNS).
Although the next version of the IP protocol offers essentially an unlimited number of unique IP addresses (see IPv6), the traditional IP addressing system (IPv4) uses a smaller 32-bit number that is split between the network and host (client, server, etc.). The host part can be further divided into subnetworks (see subnet mask).
Class A, B and C
Based on the split of the 32 bits, an IP address is either Class A, B or C, the most common of which is Class C. More than two million Class C addresses are assigned, quite often in large blocks to network access providers for use by their customers. The fewest are Class A networks, which are reserved for government agencies and huge companies.
Although people identify the class by the first number in the IP address (see table below), a computer identifies class by the first three bits of the IP address (A=0; B=10; C=110). This class system has also been greatly expanded, eliminating the huge disparity in the number of hosts that each class can accommodate (see CIDR). See private IP address and IP.
NETWORKS VERSUS HOSTS IN IPV4 IP ADDRESSES
Maximum Maximum Number of
Class Number Hosts Bits used in
Number of per Network/Host
Class Range Networks Network ID ID
A 1-126 127 16,777,214 7/24
B 128-191 16,383 65,534 14/16
C 192-223 2,097,151 254 21/8
127 reserved for loopback test
Networks, Subnets and Hosts
An IP address is first divided between networks and hosts. The host bits are further divided between subnets and hosts. See subnet mask.
 | Reproduced with permission from Computer Desktop Encyclopedia. Copyright (c) 1981-2009 The Computer Language Company Inc. All rights reserved. |
Additional Resources
- IP Shifter 2.3.7 (Windows)
- IP Shifter is a software tool that helps you to change your TCP/IP related settings easily and quickly. If you work dynamically at several locations in the network due to business, you need to be connected in different offices, or you need to use your computer in more than one...
- Software downloads 2009-11-27
- Real Hide IP 3.5.4.6 (Windows)
- Real Hide IP is easy-to-use privacy software which allows you to conceal your IP address, choose IP country and surf anonymously. It can clear cookies, protect your privacy, prevent identity theft, and guard against hacker intrusions, all with the click of a button. Using it, you can conceal your identity...
- Software downloads 2009-11-25
- OpenDNS Updater 2.2 (Windows)
- The OpenDNS Updater will run in your system tray and send updates to your account whenever your IP address changes. This will help ensure that your system preferences are applied to your network at all times. Simply download the software, enter your OpenDNS username, password and network label in the...
- Software downloads 2009-11-25
- IPNetInfo 1.21 (Windows)
- IPNetInfo is a small utility that allows you to easily find all available information about an IP address. The owner of the IP address, the country/state name, IP addresses range, contact information (address, phone, fax, and email). IPNetInfo can be very useful for finding the origin of unsolicited mail. You...
- Software downloads 2009-11-23
- WhosIP 1.05 (Windows)
- WhosIP is a simple command-line utility that allows you to easily find all available information about an IP address: The owner of the IP address, the country/state name, IP addresses range, contact information (address, phone, fax, and email), and more.
- Software downloads 2009-11-23
- VPN-X 2.4.1.39 (Windows)
- Cross-platform P2P/SSL/TLS VPN solution. Client has an individual Virtual IP Address. It can help employees on errands use company LAN resource, help your friends access your computer, play LAN games, all the network data is encrypted and you can control the special peers to access your computer or LAN with...
- Software downloads 2009-11-23
- TekPhone 1.2 (Windows)
- TekPhone is a SIP Session Initiation Protocol VoIP Softphone that provides UA agent functions (Based on RFC 3261) runs under Windows (XP, Vista, 2003 Server). TekPhone supports Only G.711 A - Mu law codecs and RFC 2833 for DTMF digit delivery and UPnP for NAT traversal. You can also set...
- Software downloads 2009-11-20
- TekSIP 2.3 (Windows)
- TekSIP complies with RFC 3261, RFC 3263, RFC 3311, RFC 3581, and RFC 3891. It supports NAT traversal. Please see technical details about NAT traversal in Readme.txt. You can select IP address to be listened and default SIP endpoint for outgoing calls. You can also log session details into a...
- Software downloads 2009-11-20
- BeeThink IP Blocker 1.2 (Windows)
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- Software downloads 2009-11-18
- Serial Port Redirector 2.3.1 (Windows)
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- Software downloads 2009-11-18
- The weirdest Easter egg ever seen on Facebook
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- Discussion threads 2009-11-17
- Auto Hide IP 4.6.2.2 (Windows)
- Auto Hide IP is privacy-protection software which enables you to conceal your real IP address, surf anonymously, and automatically change your IP address every few minutes. With it, you are able to conceal your identity online by showing them a fake IP, blocking hackers and identity theft from knowing your...
- Software downloads 2009-11-17
- Terminal Server Utility 1.0.3 (Windows)
- Terminal Server Utility is a tool enabling you to accomplish administrative tasks related to Terminal Server. Features are: monitoring; lists of session, per servers; session's details - user name - logon time, computer client name, remote address IP, incoming & outgoing traffic; process' details - list of processes, par user,...
- Software downloads 2009-11-16
- VisualRoute 2010 14.0a (Windows)
- VisualRoute combines the tools traceroute, ping, reverse DNS, and Whois into a single graphical interface that analyzes Internet connections to quickly locate where outages or slowdowns occur. An IP location database identifies the geographical location of IP addresses and Web servers, showing the path of an Internet connection on a...
- Software downloads 2009-11-15
- IP Locator 1.6.2 (Mac)
- Ever check your web logs and wonder where in the world is 84.112.1.125? (Answer: Vienna, Austria) How about 118.90.122.47? (Answer: Kerikeri, New Zealand) Wonder no more! Through the magic of geolocation, IP Locator takes that mysterious IP address and tells you where that hit to your web site (or intruder...
- Software downloads 2009-11-14
- SmartWhois 5.0 build 243 (Windows)
- SmartWhois is a useful network information utility that allows you to find out all available information about an IP address, host name, or domain, including country, state, city, name of the network provider, and administrator and technical support contact information. Unlike standard Whois utilities, SmartWhois can find the information about...
- Software downloads 2009-11-14
- IP Watcher 3.0.0.3 (Windows)
- IP Watcher is a powerful application that monitors your public and local IP address. If your IP address changes it will send an email or SMS Text Message alert containing the new WAN IP address. This alert also includes the computer name, local IP address and time the change occurred....
- Software downloads 2009-11-13
- BwanaDik 3.3 (Mac)
- BwanaDik is an IP address WAN and LAN menu item. Yes, another IP address app. Just what the world needs. You may be asking yourself "why the heck does the world need another IP address application?" Well, it doesn't. But I did. I looked all over for an IP address...
- Software downloads 2009-11-13
- Wifi File Transfer for Blackberry (Mobile)
- "I couldn't believe how amazingly easy WiFi File Transfer was to use ... I was equally impressed with the speed the transfers seemed to possess. I was also able to effortlessly create and manage new folders from my BlackBerry and from my computer."- CrackBerry "..great solution that I am surprised...
- Software downloads 2009-11-13
- Microsoft probing Windows 7 zero-day hole
- I hope Jeremy got some sleep last nightbecause he probably won't be getting much in the near future.first of many zillionsis there anything worse than being MS security programmer?poor bastards.YesYeah, being a mindless repetitive troll.yeah, being a poor Mac user. yeah, being a poor Mac user....
- Discussion threads 2009-11-12
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