Split-DNS zone file confusion

[yonatan]

I'm following the wiki Ubuntu 8.04 install guide (Ubuntu 8.04 LTS Server (Hardy Heron) Install Guide - Zimbra :: Wiki) as well as the Spilt-DNS wiki (Split DNS - Zimbra :: Wiki).

I'm stuck on the zone file creation part. Specifically I am confused how the last few lines should look because both wikis above look different.

This from from the Ubuntu guide:

;
; BIND data file for mydomain.com
;
$TTL    604800
@       IN      SOA     mail.mydomain.com. admin.mydomain.com. (
                         070725         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
@       IN      NS      mail
        IN      MX      10 mail
        IN      A       xxx.xxx.xxx.xxx
mail    IN      A       xxx.xxx.xxx.xxx

This is the Split-DNS:

;
;       Addresses and other host information.
;
@       IN      SOA     server.example.com. hostmaster.server.example.com. (
                               10118      ; Serial
                               43200      ; Refresh
                               3600       ; Retry
                               3600000    ; Expire
                               2592000 )  ; Minimum
;       Define the nameservers and the mail servers
               IN      NS      
               IN      A       
               IN      MX      10 server.example.com.

The lines I've marked in red are the ones I'm looking for help with and some explanation as to what the "@" means in the first column and also when to leave it out and replace it with "mail".

Thanks

[uxbod]

The first one is fine and will be easier to understand.

[yonatan]

Originally Posted by uxbod

The first one is fine and will be easier to understand.

Hi uxbod!

Thanks for answering. Can you please explain what it all means as this is new to me.

@       IN      NS      mail
        IN      MX      10 mail
        IN      A       xxx.xxx.xxx.xxx
mail    IN      A       xxx.xxx.xxx.xxx