Initial query speed

j.vogt at fl1.li j.vogt at fl1.li
Thu Apr 5 14:00:25 UTC 2018


Hi list

I have a hardware firewall which acts as local resolver. I want to 
replace the DNS part on the firewall with unbound and I'm using quite a 
basic configuration from CENTOS7.
The new setup is like this:
internet <-> firewall <-> unbound server

What I experience is that dns queries to domains i never queried before 
(thus making sure the query i not cached) is "slow" on on unbound.
A query to such a domain can easily take some hundreds milliseconds, 
whereas on the Firewall resolver, the same querry is rarely higher than 
100 ms.

A second querry is alway very fast (0-1 ms), which is no surprise.

When I run the provided warmup script from the package (also available 
here: 
https://github.com/breadwallet/unbound/blob/master/contrib/warmup.sh) 
this takes about 25 - 35 seconds when run for the first time.
# time /root/bin/warmup.sh
...
real	0m28.128s

Is this normal? What are your experiences? What could be the reason for 
the diverging query times on the firewall resolver and unbound?

Thanks
Josef



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