DNS Basics
The domain name system, or DNS for short, is a way to convert IP addresses into names that people can easily remember or relate to. DNS also provides information about the domain name to allow for email and other services as well. The three basic DNS records, or type of data, are an A record, an MX (Mail eXchange) and a CNAME record. The A records are used to point to where a web site or some other type service is, www.spiderhunter.com is a valid A record. An MX record point to the servers where all email is delivered for that domain or sub-domain. A CNAME record allows you to point a named server to another named server. For instance, forums.spiderhunter.com is actually pointed to apps.simpleapps.net. This is usually done while switching from one server to another, but in this case it is done to allow for multiple domains to use the same IP address for the application service hosted by simpleapps.com The A records are the most common of the ones that are used by most everyone everyday. Every time you type in a web address an A record look up is done that looks up the name and get the IP addresses for that name. (Kind of like looking up a name in the phone book and getting the telephone number.) MX records are typically transparent to the end users. Most people just send the email to somebody@somewhere.com and don’t know how it gets there. Each mail server does a DNS look up each time it needs to know where to send the email message. Typically they cache the data for a while in case more then one email message will go to the same place. The DNS look up for an MX record will return IP addresses for email servers and also their priority, the lower the priority number the higher the priority the server it and mail will be attempted to be sent there first.
