IP address

Definition: An IP address is a binary number that uniquely identifies computers and other devices on a TCP/IP network.
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.
 
What Is a Public IP Address?, What Is a Private IP Address?
Two IP addressing standards are in use today. The IPv4 standard is most familiar to people and supported everywhere on the Internet, but the newer IPv6 standard is gradually replacing it. IPv4 addresses consist of four bytes (32 bits), while IPv6 addresses are 16 bytes (128 bits) long.
 
Internet Protocol Address Notation
A network administrator sets up the addressing scheme for an IP network. When troubleshooting network problems, users sometimes also need to be familiar with how IP addresses work.

IP Address Survival Guide

How to find, change, hide and otherwise work with IP addresses

IP address are the fundamental method for computers to identify themselves on most computer networks. Every computer (or other network device) connected to the Internet has an IP address. This tutorial explains the basics of finding, changing, and hiding (your) my IP addresses.

Inside IP Addresses

IP addresses are written in a notation using numbers separated by dots. This is called dotted-decimal notation. Examples of IP addresses in dotted-decimal notation are 10.0.0.1 and 192.168.0.1 although many millions of different IP addresses exist.

• How IP Addresses Work

Finding IP Addresses

Everyone who needs to use a computer network should understand how to look up their own IP addresses. The exact procedure to follow depends on the kind of computer you use. Additionally, in some situations you may need to find the IP address of someone else's computer.

• How to Find IP Addresses

Fixing IP Address Problems

When a computer network is functioning properly, IP addresses stay in the background and don't require any specific attention. However, some common problems you may encounter when setting up or joining a computer network include:

• A computer has no IP address
• Two computers have the same IP address
• A computer has a "bad" IP address that won't allow it to "talk" on the network

To solve these problems, several techniques can be applied including IP address release / renew, setting static IP addresses, and updating the subnet ccnfiguration

Hiding IP Addresses

Your public IP addresses are shared with others over the Internet, and this raises privacy concerns in the minds of some people. IP addresses allow your Internet usage to be tracked and give some rough information about your geographic location. While there is no simple solution to ths problem, some techniques do help hide your IP address and increase your Internet privacy:

Bus, Ring, Star,

Ring Topology

In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network. To implement a ring network, one typically uses FDDI, SONET, or Token Ring technology. Ring topologies are found in some office buildings or school campuses.
Illustration - Ring Topology Diagram

Star Topology

Many home networks use the star topology. A star network features a central connection point called a "hub node" that may be a network hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet. Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)
Illustration - Star Topology Diagram

Tree Topology

Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the root of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone. Illustration - Tree Topology Diagram

Mesh Topology

Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing. A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.
Illustration - Mesh Topology Diagram

Summary

Topologies remain an important part of network design theory. You can probably build a home or small business computer network without understanding the difference between a bus design and a star design, but becoming familiar with the standard topologies gives you a better understanding of important networking concepts like hubs, broadcasts, and routes.

Network Topologies

Bus, ring, star, and other types of network topology

In computer networking, topology refers to the layout of connected devices. This article introduces the standard topologies of networking.

Topology in Network Design

Think of a topology as a network's virtual shape or structure. This shape does not necessarily correspond to the actual physical layout of the devices on the network. For example, the computers on a home LAN may be arranged in a circle in a family room, but it would be highly unlikely to find a ring topology there. Network topologies are categorized into the following basic types:

• bus
• ring
• star
• tree
• mesh

More complex networks can be built as hybrids of two or more of the above basic topologies.

Bus Topology

Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message. Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet") and 10Base-5 ("ThickNet") both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.
Illustration - Bus Topology Diagram