Article delegate-en/1506 of [1-5169] on the server localhost:119
  upper oldest olders older1 this newer1 newers latest
search
[Top/Up] [oldest] - [Older+chunk] - [Newer+chunk] - [newest + Check]

Newsgroups: mail-lists.delegate-en

[DeleGate-En] Re: Delegate 7.8.1 on W2k occasional DNS problems
24 Jan 2002 18:29:22 GMT "Ferenc Toth" <pxqcqbdyi-4mytk2vdr3zr.ml@ml.delegate.org>


On Thu, 24 Jan 2002 14:23:12 +0100, Ferenc Toth wrote:
ty.
>[...]
>
>One more thing. I've noticed that the RecvFrom errors are logged right
>after some busy time. So if delegate services multiple queries in a
>very short time, a RecvFrom error will follow. Don't ask me why are
>there multiple queries for the same domain name. (192.168.99.5 is an
>internal linux machine running bind9.2 servicing internal DNS queries
>and forwarding all other requests to delegate).
>
>01/24 13:15:46.35 [332] 0+175: {R} QUERY www.uwsg.iu.edu IN A
>01/24 13:15:46.35 [332] 0+175: [0.000s] 192.168.99.5
>01/24 13:15:46.35 [332] 0+176: {R} QUERY www.uwsg.iu.edu IN A
>01/24 13:15:46.36 [332] 0+176: [0.010s] 192.168.99.5
>01/24 13:15:46.36 [332] 0+177: {R} QUERY www.uwsg.iu.edu IN A
>01/24 13:15:46.36 [332] 0+177: [0.000s] 192.168.99.5
>01/24 13:15:46.36 [332] 0+178: {R} QUERY www.uwsg.iu.edu IN A
>01/24 13:15:46.36 [332] 0+178: [0.000s] 192.168.99.5
>01/24 13:15:46.36 [332] 0+179: FATAL RecvFrom(9) = -1, errno=0
>01/24 13:15:56.37 [332] 0+180: FATAL RecvFrom(9) = -1, errno=0
>[...]

Some more investigation revealed that the sequence of the events are
the followings:

o there is a DNS query that takes unusally long time to complete (from
1.5s to 22s!) (we've a 256kbit permanent connection to our ISP and
we're using their name servers).
o there are multiple DNS requests queued meanwhile that are now
executed
o and these bunch of DNS queries cause some data overrun? resulting in
-1 for RecvFrom() (it looks to me that the number of RecvFrom() errors
is usually proportional to the amount of queued DNS queries)

Can you please add a few debug lines to figure out what can cause the
first unusally long DNS query? Or tell me what piece of code to look
for so I can add the debug statments myself (I can do some c
programming, though I am by no means a guru :). I could successfully
compile 7.8.1 with the cygwin environment on Windows.




  admin search upper oldest olders older1 this newer1 newers latest
[Top/Up] [oldest] - [Older+chunk] - [Newer+chunk] - [newest + Check]
@_@V