CNAME question

[Brad Knowles]

At 8:06 AM +0700 7/27/01, viet anh wrote:

>  vietanh.com IN SOA dns.domain.com mail.dns.domain.com
>  (

	Won't work.  The open parenthesis character must be the last 
thing on the line above.

>  My question here is that: is there any problem if I
>  add only CNAME record after NS record.
>  File vietanh.com.dns will like that:
>  vietanh.com IN SOA dns.domain.com mail.dns.domain.com
>  (
>                        20010725;
>                        86400;
>                        86400;
>                        3600;
>                        3600000;)
>  vietanh.com    IN NS dns.domain.com.
>  vietanh.com    IN  CNAME www.isp.com.

	Nope.  Won't work.

>  Because as my knowlege, the CNAME record can't exist
>  with any record.

	That's right.  Now, you could CNAME www.vietanh.com to something 
else, but that's a different matter.

	Oh, and make sure you either use unqualified names (don't include 
the domain name), or place a trailing dot at the end of the FQDNs, 
because you don't want:

		vietanh.com			IN	NS	dns.domain.com.

	To be mis-interpreted by BIND as:

		vietanh.com.vietanh.com	IN	NS	dns.domain.com.

>  one computer will have only IP address and one name.
>  if I want this copumter have another name I have to
>  declare CNAME record in DNS that point to the first
>  name of this computer.

	You could do that, yes.

>                          But I have a problem with mail
>  exchanger ( my domain have CNAME and MX record). I
>  want to replace CNAME record by A record, so one ip
>  address will have two A record, for example:
>   mail.vietanh.com IN A 10.0.0.1
>   mail.isp.com     IN A 10.0.0.1
>   I wonder if my dns system work
>  correctly.

	Yup, that should work just fine.  Of course, you want to make 
sure that you use real IP addresses.  ;-)

>  As DNS administrator, if I declare like that, what
>  problem I have to take care?
>  ( at this time, declare like that, it will work fine)
>  I am looking forward to have your answer.

	The one thing to watch out for is the reverse DNS configuration 
for this IP address.  You should decide which name you want everyone 
in the world to see when this machine connects out to others in the 
world, and make that the one name you list in the reverse DNS file 
for this IP address.  Don't list more than one name for the same IP 
address, because most applications either ignore the extra 
information or do not function correctly.

-- 
Brad Knowles, <brad.knowles at skynet.be>

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