Now it's time for your crash course in Internet Protocol. This is a brief, simplified introduction to what IP is and how your network and the Internet use it
IP is part of the TCP/IP suite of protocols that have become the global standard for Internet communications. The TCP/IP protocol contains dozens of protocols, but the name refers to two of the most important the Transmission Control Protocol (TCP) and the Internet Protocol IP. The IP protocol provides addressing that makes TCP/IP communications routable. This means that all messages transmitted over a TCP/IP network are marked with the IP address of the destination network and station.
TCP/IP networks use a technology called packet switching. On a packet-switched network, computers divide data into smaller, individually addressed packets. Because each of these data packets contains a destination address, they can be switched or follow different paths to reach their destination. Contrast this with a circuit-switched network, like the telephone system, in which communications require a dedicated point-to-point connection.
A packet-switched network uses network bandwidth more efficiently because users can share bandwidth, all of them sending their packets at the same time. Routers direct each of the individually addressed packets to its proper destination, where the destination computer reassembles the packets into the original message. IP packets don't have to reach their destination in the proper order; each packet contains sequencing information in its address header.
Because of the way data travels over the Internet, each computer must have a unique IP address. An IP address is four sets of numbers separated by decimals. For example, your IP address may look something like this, 220.127.116.11. IP addresses are divided into classes. Class A addresses start with a number range of 1-126. Class B addresses start with a number range of 128-191. Class C addresses start with a range of numbers from 192-223. (Don't worry about remembering this; it's just nice to know. There won't be a test later.)
The following address ranges are reserved for intranet (internal) addresses, which are used on internal networks like your WLAN. These address ranges aren't routable over the Internet.
- 10.0.0.0 to 10.255.255.255
- 172.16.0.0 to 172.31.255.255
- 192.168.0.0 to 192.168.255.255
To configure a network connection, you need to know three addresses:
- Your IP address
- Subnet mask
- Default gateway
Your IP address is the address of your computer and is assigned to you by your ISP. Technically, this is the address of your modem. When you share the connection on your network, your router gives you an intranet address. Your IP address can be permanent, or your ISP can dynamically reassign it each time you reboot or reconnect (using DHCP). An example IP address is 10.4.38.171.
Your subnet mask represents the portion of the IP address range that refers to subnet addresses. An ISP can divide its assigned IP address range into subnets. In this subnet mask example, 255.255.255.0, the first three numbers (255.255.255) represent the part of the IP address range that identifies subnets, and the last number (0) identifies hosts on that subnet.
This means that, with the example BP address 10.4.38.171, the numbers 10.4.38 identify the subnet. The number 171 identifies my computer on that subnet. A computer with the IP address 10.4.37.171 is on a different subnet.
The default gateway, for example, 18.104.22.168, is the address of the computer or router that you use to connect to the Internet. In most cases, your ISP provides you with the addresses you need to connect to its network, or a DHCP server assigns them automatically.
Insider insight:" you noticed that the IP address given in the example above is an intranet address, good job. You've scored extra points. Some broadband ISPs assign their customers intranet addresses and then have them connect to the Internet via router or server. This conserves public, mutable IP addresses and provides some additional security.
Because the intranet address is not routable, the ISP must perform Network Address Translation (NAT). Using NAT, several customers share the same publicly visible IP address that the server assigns. The result is that the address is not unique to your computer.
This adds a layer of security because people outside the ISP's network cannot send traffic to your machine unless you request it It also can wreak havoc with services that need to know the exact IP address of your machine, such as VPN.