bin/51313: named caching server timeouts

[Hauke Fath <hf%spg.tu-darmstadt.de@localhost>]

>Number:         51313
>Category:       bin
>Synopsis:       named caching server timeouts
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 05 13:55:01 +0000 2016
>Originator:     Hauke Fath
>Release:        NetBSD 7.0_STABLE
>Organization:
Technische Universitaet Darmstadt
>Environment:
	
	
System: NetBSD Gstoder 7.0_STABLE NetBSD 7.0_STABLE (MONOLITHIC) #1: Fri Apr 1 14:41:59 CEST 2016 hf@Hochstuhl:/var/obj/netbsd-builds/7/i386/sys/arch/i386/compile/MONOLITHIC i386
Architecture: i386
Machine: i386
>Description:

	We have a named instance running on a XEN DomU that caches the
	group's dns requests.

	After switching from netbsd-5 to netbsd-7, users report
	intermittent UI hangs that feel a lot like DNS failures, and
	the named log has plenty of lines like


Jul  5 12:43:40 Cellon named[631]: client 0x7f7ff07d1800 (e1948.a.akamaiedge.net): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff07d1800 (springer.com.edgekey.net): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff0def800 (video-stats.l.google.com): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff0df3000 (0.client-channel.google.com): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff0df1000 (0.client-channel.google.com): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff0df2800 (doodle.com): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff0df0000 (blocklist.addons.mozilla.org): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff07d2800 (services.addons.mozilla.org): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff0def000 (kicker.de.122.2o7.net): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff0dee000 (kicker.de.122.2o7.net): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff0dec800 (imap.gmail.com): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff5377000 (cs485.wac.gammacdn.net): query_find: unexpected error after resuming: timed out
Jul  5 12:43:50 Cellon named[631]: client 0x7f7ff43dd000 (dns.msftncsi.com): query_find: unexpected error after resuming: timed out

	See also
	<https://mail-index.netbsd.org/netbsd-users/2016/03/24/msg018231.html>.

	
>How-To-Repeat:

	Set up a caching nameserver on netbsd-7.

	
>Fix:

	For now, we are back to the netbsd-5 DomU which does not
	exhibit the problem.

>Unformatted: