External DNS Records-A record or CName?

[LostinIT]

I'm a little confused with WHAT type of record I should be using with my domain name registar (GoDaddy.com) to point my subs to my network; 'A' records or CNAME records? Are they identical? Or can someone point me to an article (DNS 101 type article, PLZ) explaining the differences.

Here is a list of the names I want pointed to my network:

ftp.mysite.com
smtp.mysite.com

My gratitude ahead of time....

 

[Kreichek]

Usually you would want to create A records. An A record maps a domain name to the corresponding IP address. A CNAME record maps a domain name to another domain name (also called an "alias"). This means that with CNAME you can have e.g. two domain names pointing to a single IP address. Example:

ftp.mysite.com. IN A 192.168.0.1
smtp.mysite.com. in CNAME ftp.mysite.com.

This means that if you query the nameserver for ftp.mysite.com it will result in an answer of 192.168.0.1. If you query for smtp.mysite.com and you want to get the IP address, then the resolver finds out that there is no A record fo smtp.mysite.com, but there is a CNAME. It will start a new query for the name which stays right of the CNAME statement and this will result in finding the appropriate IP address. Be careful not to put names in the right which do not have any other CNAMES or A records since this will cause a "non-existent domain" message to be returned to the client.

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Jordan Jordanov
Network administrator
Faculty of German Engineering Education and Industrial Management
Technical University of Sofia, Bulgaria