[Pdns-users] Full cache and packet cache behavior

[Artur Russu]

Hello All,

DNS server configuration:
Host - ESXi VM
CPU - 4 cores @ 2GHz
RAM - 2GB
Pdns-recursor - PowerDNS Recursor 3.3

Currently, the cache and packet cache are set to 1000000 limit by configuration:
            max-cache-entries=1000000
max-packetcache-entries=1000000

As I understood from provided configuration, this is a per thread configuration, and actually we'll have 4000000 records if 4 threads are used.
Now, our caches are full, as can be seen from rec_control:
  rec_control get cache-entries packetcache-entries
  1001003
  1001090

My questiones are what is the behavior of pdns-recursor if a new request, not known by the recursor, is issued by our clients?
What will it do with the received response?
Is it OK to have the caches full all the time? We see that many of our clients are issuing requests for non-existing domains, filling the cache with NXDOMAIN records.
Where can I read more about this process?

Thank you.
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