Maintained by: NLnet Labs

[Unbound-users] patch implementing round robin rrsets

David Miller
Wed Mar 7 18:01:29 CET 2012

On 3/7/2012 10:49 AM, Tony Finch wrote:
> Olaf Kolkman <olaf at> wrote:
>> But you could reasonably ask whether those load balancing properties
>> should be under the control of the authoritative or the recursive name
>> server.
> Indeed :-)
> The problem with saying it must only be the authority's job is that in
> situations like ours (which being a university is I guess not that
> different from Thijs's) the user population do not use very many different
> resolvers, so the authorities do not get the opportunity to serve up lots
> of different RR set orderings, unless you go for ridiculously short TTLs.

Since the order of RRs in a set is not significant, then load balancing
through the use of
multiple RRs at a name could only be an attempt to evenly distribute between
addresses/hosts.  Randomization of records within a set at the resolver
level will only
improve the even distribution between hosts.

[RFC 1034]

3.6. Resource Records

A domain name identifies a node.  Each node has a set of resource
information, which may be empty.  The set of resource information
associated with a particular name is composed of separate resource
records (RRs).  The order of RRs in a set is not significant, and need
not be preserved by name servers, resolvers, or other parts of the DNS.

Those who desire finer control over weight for hosts in load balancing
need to implement
this through SRV records - which provide this functionality... and then
join the crowd
complaining to those who make clients that don't support SRV records.