Re: Tips for DNS zone administration

[Mats Dufberg <dufberg@nic-se.se>]

On Sat, 21 Apr 2001, Sam Trenholme wrote:

>      * Never have the same computer names used for NS records for your
>        domain be used for anything else, such as MX records or CNAME
>        records.

I know that CNAME must not be combined with MX or NS in the same node, but
what combinations of NS and MX are bad?


>      * If possible, make the TTLs for the NS records for your domain as
>        long as possible (604800 seconds--one week, is a good number).
>        This will speed up accesses to your domain, since caches will not
>        have to query the root servers as often before querying your name
>        servers.

If you do remember to set it down well before any changes... I think that
TTL's over 1-2 days should be well motivated before use.

Instead, recommend a long expire. I've seen 1 hour in zones... A week or
two is usually good.


>      * Never have a CNAME record and any other record use the same host
>        name. This will confuse caching nameservers, which usually assume
>        that a CNAME record applies to all record types for a given host
>        name.

A "host name" is a node in the domain tree which has an A record, isn't
it? -- "Never have a CNAME record and any other record in the same node."

>      * Avoid using CNAME records--they can increase the number of DNS
>        queries needed to resolve a given host name.

"In the same zone it is usually better to let several names have A records
pointing at the same IP addresses."


Mats

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Mats Dufberg                                     +46-8-545 857 06
dufberg@nic-se.se                           fax: +46-8-545 857 29