Assuming that you do plan to use your home network to share an Internet connection, one addition piece of information that you’ll need to supply as part of the TCP/IP configuration of computers is the IP address of one or more DNS servers. DNS is the domain name system, which is responsible for translating fully qualified domain names (FQDNs) into IP addresses on the public Internet. For example, when you attempt to access the PC Answers website, you would typically submit the FQDN www.pcanswers.co.uk in the address bar of your web browser. While this name is easier to remember than the IP address of the PC Answers website, TCP/IP ultimately requires the IP address of the site in order to make communication possible. The “resolution” of FQDNs to IP addresses on the public Internet is the primary responsibility of DNS servers.
The IP address that you would enter in the DNS server address section of your TCP/IP properties typically belongs to a DNS server of your ISP. This information is usually provided by the ISP when sign up for their service. This is not to say that it is impossible to host your own DNS server on your network, because it is indeed possible. However, most home network users really have no need for an internal DNS server, a topic that we’ll explore further in future articles in this series.
One thing that you’ll notice with the configuration of DNS settings is that Windows versions allow you to configure the IP addresses of both a “preferred” and “alternate” DNS server (the terms used differ between Windows versions). The main reason for this is redundancy. If your computer attempts to contact one DNS server to resolve a name to an IP address and the server is unavailable, the second DNS server will be sent the queries. One DNS server IP address is usually sufficient, but if this server becomes unavailable, you would no longer be able to resolve names correctly, so configuring both is a good idea. Unless, of course, you want to try to remember the IP address associated with every website you ever visit – certainly not a simple task.