Re: DNS hiccups

On Wed 16/Apr/2025 01:30:08 +0200 Sam Varshavchik wrote:
> Alessandro Vesely writes:
> 
>> There is no AAAA record.  The A queries seem to have timed out after 5, 
>> although in resolv.conf I have "options timeout: 10".  IIRC Courier does read 
>> resolv.conf.  Why didn't it wait 10?
> 
> Courier's code reads resolv.conf, but only parses the domain and NS IP 
> addresses from it. Courier's own resolver will try three times to get a 
> response, with a 5 second timeout, then a 25 second, then a 125 second on the 
> last try…


Got it.  Thank you.


> So, there were multiple attempts made, here.


Only two A queries were logged.  Unfortunately, named log doesn't tell the 
result, but someone on bind-users noticed that the name servers for 
mail.protection.outlook.com return FORMERR for EDNS queries (5 years after the 
DNS flag day).  Maybe the first query timed out and the second gave error?

I guess the resolver tries with no edns after a FORMERR.  That explains how the 
following messages to the same MX passed.


Best
Ale
-- 





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