Warning Subnetcache

Unbound
1

Hi, on Debian 12.1 with Unbound 1.17.1 I get the following warning: (see warning in bold below)

Aug 19 13:02:51 rpi4-20210823 systemd[1]: Starting unbound.service - Unbound DNS server…
Aug 19 13:02:51 rpi4-20210823 unbound[557]: [557:0] notice: init module 0: subnetcache
Aug 19 13:02:51 rpi4-20210823 unbound[557]: [557:0] warning: subnetcache: prefetch is set but not working for data originating from the subnet module cache.
Aug 19 13:02:51 rpi4-20210823 unbound[557]: [557:0] notice: init module 1: validator
Aug 19 13:02:51 rpi4-20210823 unbound[557]: [557:0] notice: init module 2: iterator
Aug 19 13:02:52 rpi4-20210823 unbound[557]: [557:0] info: start of service (unbound 1.17.1).
Aug 19 13:02:52 rpi4-20210823 systemd[1]: Started unbound.service - Unbound DNS server.
Aug 19 13:04:54 rpi4-20210823 unbound[557]: [557:0] info: generate keytag query _ta-4f66. NULL IN

Is that a problem? How can I solve that?

I did not have that warning with Debian 11.

Thanks, George

Georg Fronapfel
Am Weidengarten 11
61476 Kronberg
Tel: 06173/3274874
Mobil: 01512/2369069
Fax: 06173/9969854

2

Hi Georg,

Probably the compilation or the default configuration of Unbound changed between those Debian versions.

This is only a problem if you want the prefetch functionality to work with the subnetcache module (ECS); which currently it does not.

You can turn either off and the warning would go away.

If Unbound was compiled with ECS support, the subnetcache module is by default enabled in the configuration. To turn it off you need to explicitly set a module-config without it, for example:
     server:
         module-config: "validator iterator"

Best regards,
-- Yorgos