[Pdns-users] Sub-domains and zones

Brian Candler b.candler at pobox.com
Fri Jun 18 07:22:14 UTC 2021

On 18/06/2021 05:16, Daniel Miller via Pdns-users wrote:
> Given a published zone of ".myzone.com" - I want to have a list of 
> hosts like:
> a.sub.myzone.com
> b.sub.myzone.com
> c.sub.myzone.com
> Nothing special. I can implement this by explicitly declaring each 
> host in my parent zone - and this works. But I want to manage the 
> subdomain separately. So besides creating a zone ".sub.myzone.com" and 
> adding the host records - what other "glue" is required?
> Do I need to explicitly publish ".sub.myzone.com" with my registrar?
> Do I place NS records for ".sub.myzone.com" in the parent zone?
Yes.  This is the delegation.  The nameservers for sub.myzone.com aren't 
necessarily the same as those for myzone.com.
> Do I place NS records for ".sub.myzone.com" in the sub-zone?

Yes.  This is the authoritative source of the NS records.  (I always 
thought this was a weird aspect of DNS design, as having two sources of 
info makes it likely that they will be inconsistent, but that's how it 
is.  Just make sure they match.)

> Do I need to explicitly declare a forward-zone for ".sub.myzone.com" 
> in addition to the parent zone?


In any case, there's no such thing as a forward-zone in an authoritative 
DNS server; that would be something in a recursor. But the recursor can 
just follow the NS records.  You shouldn't even have a forward-zone 
entry for myzone.com.

The only exception would be if this is if myzone.com is a private 
domain, which is not delegated in the public DNS.  In that case, you 
will need a forwarding entry for sub.myzone.com - but only if you're 
forwarding to a different set of servers than myzone.com.



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