Tuesday, November 19, 2013

Host Names

How are host names made up?

Well, first of all, host name strings are a nice way to represent a network server, so that we don't have to remember a lot of numbers. (See Internet Addressing)

Host names usually have letters, sometimes numbers, and dots. The dots are not just to make them easier to read, they are "canonical". What that means is that the dots separate parts of the host name into different sized groups.

Most of the host name that you see, for example the "" part of "", is the domain name of the host. A domain is a bunch of computer systems all assembled under the same organization. So, for instance, Google manages all the computers in the "" domain (not to mention and a few others).

The ".com" part of the domain name is also a bunch of computers in the same organization, but of course they're not all owned by one company. But there is an organization for each top-level domain, and they decide if you are allowed to have your domain be a part of their structure.

Most examples you will see of host names have three parts - the host itself (www, perhaps), the company domain, and the top-level domain. But you can actually have sub-domains and sub-sub-domains and so on. So Google might have a host name like

Perhaps you are thinking "wow, so is a network server. That must be one big machine to handle so much traffic!". Well it could work that way, but there are some tricks that domain administrators can use to do resource pooling and load sharing, so actually represents a whole bunch of servers. But don't worry about that part just yet.

You might be interested in:
  • IP Networks and Subnets
  • IP Routing
  • Dynamic Name Service (DNS)
  • Dynamic Host Configuration Protocol (DHCP)

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