DOMAIN NAME SYSTEM (DNS) - COMMON TYPES OF DNS REQUESTS

DNS Basics
Common Types of DNS Requests
Handling Your DNS Records

A-type request

The most common request is the `A' type request, or put simply, a query like "what is the IP address of this host?". For example, when you access www.webhostingmenu.com, your browser first makes an "A-type" DNS query in order to determine the IP of www.webhostingmenu.com (which is 64.90.177.50). It then connects you to 64.90.177.50.

As a result, users don't have to remember numerical addresses and webmasters don't have to make their address permanent - if it changes (for example, when moving between web hosting providers), a simple change of the site's DNS record takes care of the logical address "continuity".

CNAME-type request

Another type of requests is the CNAME request. CNAME requests return the "canonical" name of a given host. For example, CNAME of www.google.com is www.google.akadns.net. By doing an A-type request on www.google.akadns.net one can determine that the host has two IP addresses: 216.239.51.99 and 216.239.51.104. This extra layer of redirection is needed for simplifying a complex network structure.

Again, this type of request is usually performed automatically by the browser and the end user does not notice it.

Mail record request (MX record)

Finally, the third most popular DNS request type has to do with delivery of electronic mail.

Let's say you have an e-mail address self@mybusiness.com. By querying the DNS server for "MX record" of mybusiness.com, one can find out that all e-mail for the domain mybusiness.com is handled by the mail server running at smtp.mybusiness.com. Thus, all mail address to you (self@mybusiness.com) will be sent to smtp.mybusiness.com for processing.

For information on other, less popular types of DNS records, see this page.