In the last part of this article series, I talked about how all of the computers on a network segment
share a common IP address range. I also explained that when a computer needs to access information from a computer on another network or network segment, it’s a router’s job to move the necessary packets of data from the local network to another network (such as the Internet).
If you read that article, you probably noticed that in one of my examples, I made a reference to the IP address that’s associated with my Web site. To be able to access a Web site, your Web browser has to know the Web site’s IP address. Only then can it give that address to the router, which in turn routes the outbound request packets to the appropriate destination. Even though every Web site has an IP address, you probably visit Web sites every day without ever having to know an IP address. In this article, I will show you why this is possible.
I have already explained that IP addresses are similar to street addresses. The network portion of the address defines which network segment the computer exists on, and the computer portion of the address designates a specific computer on that network. Knowing an IP address is a requirement for TCP/IP based communications between two computers.
When you open a Web browser and enter the name of a Web site (which is known as the site’s domain name, URL, or Universal Resource Locator), the Web browser goes straight to the Web site without you ever having to enter an IP address. With that in mind, consider my comparison of IP addresses to postal addresses. You can’t just write someone’s name on an envelope, drop the envelope in the mail, and expect it to be delivered. The post office can’t deliver the letter unless it has an address. The same basic concept applies to visiting Web sites. Your computer cannot communicate with a Web site unless it knows the site’s IP address. Networking Basics: Part 3 - DNS Servers
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