Recommendations for DNS

> Ex:
>  
> foo.bar.com.        IN      SOA     dns.foo.bar.com admin.foo.bar.com 

Add trailing dots if this is supposed to be in master file format.

> MX       When pointing a domain to a mailserver/hostname, do not forget
>          to add a record ( A ) for this.

... if and only if that target resides in the very same zone.

> CNAME    Use this with caution. It is *not* recommended to use a CNAME
>          for a mailservers hostname, as this can cause resolving problems
>          and mailloops. Also it is not a good thing to use CNAMES on
>          nameservers as this will cause unnecessary traffic on the net.

Both are not only bad practice but forbidden by the protocol.

>Unecessary glue data:  
        
>	Do not add unecessary glue data about hosts that is not within
>	the zone. This can cause resolving problems if the host changes IP
>	address.
> Ex:
>  
> foo.bar.com.        IN    MX      10 mail.foo.bar.com.
>  
> mail.foo.bar.com.    IN    A       192.168.0.1

Is this an example of what *not* to do? So how does it differ from the
suggestion a few lines above? Otherwise, the term "glue" data is wrong.
The only valid purpose of glue A RRs is to provide for the address of
a nameserver residing in the domain tree in or below the zone it is delegated.
 
> Example on a recommended DNS:

s/DNS/zone file/

> foo.bar.com  IN    SOA     ns.foo.bar.com. root.foo.bar.com. (
>                         1998081900      ; serial
>                         28800   ; refresh (8 hours)
>                         7200    ; retry (2 hours)
>                         1209600 ; expire (14 days)
>                         86400 ) ; minimum (1 day)
> foo.bar.com.  IN    NS    ns.foo.bar.com.
>  
> foo.bar.com.    IN  NS    ns2.foo.bar.com.
>  
> foo.bar.com.  IN    MX    10 mail.foo.bar.com.
>  
> www.foo.bar.com.  IN  CNAME www.webhotel.xx.
This cannot really be recommended. Extra zone CNAME-RRs have been the subject
of long discussions and in most cases they are unnecessary. What users try
to resemble by this is user-level aliasing, which is probably not a good
idea here.

> www2.foo.bar.com. IN    A       192.168.0.3
> ns.foo.bar.com.   IN    A       192.168.0.1
> ns2.foo.bar.com.  IN    A       192.168.0.4

Having the zone served by only two nameservers inside that zone cannot be
recommended. Especially, they're very likely connected to the same fuse, should
"IP distance" reflect physical distance, which often holds :-)

-Peter