Hostname DNS not resolving

[mnstrgns]

I have a server (server123 for the purposes of this post) with several domains hosted on it

the server name is
server123.server123.com

All of the domains resolve properly
They all use the dns
ns1.server123.com and
ns2.server123.com

I get error messages on emails going out as nobody@server123.server123.com
that the server name cannot be resolved

(the nobody@ is a seperate issue which I will address after I have fixed this)

If I do a DNS report, I get
[ERROR: The parent servers say that the domain shifteight02.com does not exist.]

If I try to enter the domain www.server123.com or server123.com into a browser, I get server not found
I cannot ping the server at www.server123.com or server123.com
If I try to enter ns1.server123.com or ns2.server123.com into a browser, I get a default CPanel screen for ns1 and a default web page for ns2.

How can domains on the box resolve properly, but the box domain itself not?

The domain DNS points to the same ns1 and ns2 as the rest of the domains on the box that resolve properly.

I have searched the forums extensively, and edited several files as recommended, as well as running various scripts.

I am at a bit of a loss.

Any thoughts?

[WebScHoLaR]

Have you added the A record for server123 in the DNS zone file of server123.com?

[mnstrgns]

Contents of var/named/server123.com.db

; cPanel 10
; Zone file for server123.com
$TTL 14400
@ 86400 IN SOA ns1.server123.com. server123.gmail.com. ( 2005122000 $
86400 ; refresh, seconds
7200 ; retry, seconds
3600000 ; expire, seconds
86400 ) ; minimum, seconds

server123.com. 86400 IN NS ns1.server123.com.
server123.com. 86400 IN NS ns2.server123.com.

server123.com. IN A 69.93.38.186

localhost.server123.com. IN A 127.0.0.1

server123.com. IN MX 0 server123.com.

mail IN CNAME server123.com.
www IN CNAME server123.com.
ftp IN A 69.93.38.186
ns1 14400 IN A 69.93.38.186
ns2 14400 IN A 69.93.38.187
server123 14400 IN A 69.93.38.186

[WebScHoLaR]

If you PM me the original site name and the IPs then I can see what is wrong with it.

[WebScHoLaR]

I've sent PM to you.Please check it.