Can we define masters as hostsname?

Mark Andrews marka at
Wed May 23 23:34:34 UTC 2018

> On 23 May 2018, at 11:01 pm, Matthew Pounsett <matt at> wrote:
> On 23 May 2018 at 07:37, Blason R <blason16 at> wrote:
> Hi Guys,
> Can we define masters as hostname instead of IP address? I guess its not possible but wondering if community can shed come light on this?
> The short answer.. no, you can't do that. The definition for the slave zone statement's 'masters' option (BIND 9.11 ARM pp 139) is pretty clear that you can only use IP addresses and named masters lists.  You could fake it by defining a named master list (pp. 70) but I suspect that isn't going to do what you want.  
> I think the rationale for not allowing hostnames there is that you can easily put yourself in a unresolvable (pardon the pun) situation where your slave can't reach the master until your slave reaches the master and gets a copy of a key zone.   I can also see the potential for complication even if there weren't a catch-22 in the configuration, such as what to do if the hostname referenced has multiple addresses associated with it; that would have implications for things like how complex it is to track whether a master is available or not.  I'm sure there are other complexities I haven't thought of.

Adding support for this has been on my private todo list for years.  It’s
definitely possible to do but it does require ignoring local copies of zones
and the server’s addresses when looking up the addresses for the master.

Add to that automatic registration of server addresses in the parent’s zone.
This is possible to do with UPDATE and TSIG or SIG(0) for authentication.

Add to that automatic updating of the NS RRset in the parent zone again using
UPDATE and TSIG or SIG(0).

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Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
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