A Record/CNAME Record

[David Botham]

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Before I start:  Get DNS and BIND, 4th Edition.  In that book you
will find the answers to almost all of your DNS questions...


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> Hi:
> I'm trying to understand the difference between A records and CNAME
> records.
> Basically, I'm not knowledgeable about DNS and want to understand
> more.  
> 
> I hear of people saying, "DNS alias" and I do not know if they are
> referring to
> an A record or CNAME.
> 
> Here's an example, hope you can help clarify more:-
> 
> abc.domain.com
> Is this an A record? If yes, then what is whatever.abc.domain.com?

No, here is an A record for the above:

abc.domain.com.	A	192.168.1.1 

An A record associates a hostname with an IP address.

Here is a cname record that is related to the above:

123.domain.com.	CNAME	abc.domain.com.

A CNAME record is an "alias" for another record, in this case an A
record.

Now, "whatever.abc.domain.com" could be a lot of things.  In the
domain "domain.com, it could be either an A record for a host called
whatever.abc.domain.com or, if use like this:

Whatever.abc.domain.com.  IN NS ns1.whatever.abc.domain.com.

it would be a subdomain.  However this is considered, in some
circles, an advanced topic in DNS.  

You should definitely take the time to read DNS and BIND if you are
interested in this subject...

Dave...

> 
> What then is an alias? Can you give me an example?
> 
> Thanks
> 
> ----------------------------------------
> pls reply to speedoflight at cosmo.com

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