Size limit on unbound.conf or forward zone Files?

George Thessalonikefs george at
Fri May 7 09:38:42 UTC 2021

Hi Daniel,

There is no actual size limit.

There is a limit on the system's memory though, since unbound will need 
to have internal data structures for the forwarders.
You will reach that limit when unbound refuses to start because it is 
out of memory.

Best regards,
-- George

On 05/05/2021 20:35, Guevara, Daniel via Unbound-users wrote:
> Hello,
> I have looked through several docs and have not found whether there is a 
> size limit (file or number of entries) for forward zones. We plan to use 
> unbound strictly as a forwarding DNS server and use two “include:” 
> statements in “unbound.conf” to load forwarding zone files. One such 
> file has almost 2000 domains configured.
> I have ran “/usr/sbin/unbound-checkconf” and there are no erors 
> reported. I’d just like to verify if there is a limit to the number of 
> forward zones or file size.
> Thanks!
> -- 
> Daniel

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