[Pdns-users] Spikey response times in powerdns recursor
bert.hubert at netherlabs.nl
Wed Mar 17 11:26:20 UTC 2010
On Wed, Mar 17, 2010 at 11:16:40AM +0000, Simon Bedford wrote:
> >Mar 17 11:57:02  bbc.co.uk.: Resolved 'bbc.co.uk.' NS ns1.bbc.co.uk. to: 188.8.131.52
> >Mar 17 11:57:02  bbc.co.uk.: Trying IP 184.108.40.206:53, asking 'bbc.co.uk.|A'
> >Mar 17 11:57:04  bbc.co.uk.: timeout resolving
> It never used to happen before 23/12/09 though looking at our graphs
> and as you say this happens for at least 5 domain names that we
> monitor (some of which are our own and some external).
bbc.co.uk still has a nameserver that is down, so having that domain resolve
slowly every once in a while is to be expected.
You've indicated you've occasionally seen 500ms lookups times for
google.com, but I have not heard of any other problems.
google.com takes between 0 and 100ms to resolve in my tests.
> >This matches the expectations.
> Doubling overnight and acceptable to have 2 second look up times??
> This is definitely not something that would be acceptable to our
> customers for valid domains...
These measurements from dnsscope are for _all_ domain names, not just valid
domains. Please do not think that I recommend 2 second lookup times.
The reality is that a huge number of domains have unresponsive nameservers.
Your graph indicates that 1% of queries takes between 1024 and 2048 msec to
resolve at night, and this is entirely to be expected.
A doubling of *average* response times, but still in the <40ms range, is
entirely to be expected on a server that is relatively idle at night.
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