Re: squid, DNS and no buffer space

On Tue, 3 Dec 2024, Lloyd Parkes wrote:
> On Mon, 2024-12-02 at 15:11 +0000, Stephen Borrill wrote:
>> On a busy squid proxy server, users are seeing performance problems
>> and
>> squid is logging the following:
>>
>> 2024/12/02 15:00:06 kid1| comm_udp_sendto FD 9, (family=2)
>> 127.0.0.1:53: (55) No buffer space available
>> 2024/12/02 15:00:06 kid1| idnsSendQuery FD 9: sendto: (55) No buffer
>> space available
>>
>
> Now I remember, I have seen this before. BIND assumes it's running as a
> forwarder for an ISP and that it will therefore be expected to cache
> the entire Internet's DNS. It will use all available memory.
>
> I had to add the following
>
> 	max-cache-size 25%;
>
> to the options block in my named.conf to get reasonable behaviour on my
> multi-purpose server.

I did look at top at the time to see if named was being particularly 
greedy, but didn't spot anything. I will look more closely next time, but 
interactively I don't recall any delay doing DNS lookups.

Changing that setting is a good shout though. One of my co-workers was 
using our internal resursive DNS to clean a huge domain blacklist and
hit exactly the problem you describe.

-- 
Stephen