Re: dnscache and oversized answers

>> One of my users noticed that MX lookups for xo.net were timing out.
>
> Has  this been  reported to  XO? Granted  they may  not fix  it, but  it
> doesn't hurt to point out their stupidity.

If I could figure out who to tell, I would.

> Failing that, why  not just take their highest preference  MX record and
> put it into  your smtproutes file and  be done with it.  Sure, you won't
> get any updates, but then their DNS is broken so what can they expect.

Take a look at them.  Their servers are doing load balancing by rotating 
the answers.  I did stick in an smtproute entry, but the recently offered 
patch will let dnscache deal with the next funky DNS server without having 
to hand edit stuff.

>> The problem turns out to be that  XO's name servers are putting in too
>> many additional section records and are returning oversized answers of
>> about 540 bytes, which dnscache then throws away.
>
> I assume this is because XO's  name servers aren't setting the truncated
> bit?

No, take a look at them.  It's because they're returning answers bigger 
than 512.  The answers have large additional sections which I'd just trim 
back to fit.

Regards,
John Levine, [email protected], Primary Perpetrator of "The Internet for Dummies",
Information Superhighwayman wanna-be, http://www.johnlevine.com, ex-Mayor
"More Wiener schnitzel, please", said Tom, revealingly.