new rawhide glibc

Michal Jaegermann michal at harddata.com
Fri May 23 16:48:24 UTC 2008


On Fri, May 23, 2008 at 08:08:52AM -0700, Ulrich Drepper wrote:
> > nscd is not installed. I have not used it at any point. Did try on
> > another machine and against different nameservers with the same result.
> > One machine has search in resolv.conf the other doesn't.
> > 
> > # curl www.newegg.com
> > curl: (6) Couldn't resolve host 'www.newegg.com'
> 
> The problem I saw and which I fixed was that the server answering for
> that domain deliberately doesn't reply to IPv6 (T_AAAA) queries.  I.e.,
> it depends on the client to time out.

A DNS record for www.newegg.com is broken in more ways that one.
It is possible to get 204.14.213.185 but 'host 204.14.213.185'
replies with "Host 185.213.14.204.in-addr.arpa. not found:
3(NXDOMAIN)"

> That's terribly bad practice and the provider should change that.

Good luck with that.  I have an impression that a quality of
DNS records in general goes downhill and talking to providers
is, in my experience, absolutely unproductive.  If anything the
mess is getting worse even faster.

OTOH even when records are ok then for alias names a name resolution
"stutters".  For example:

$ host www.ualberta.ca
www.ualberta.ca has address 129.128.98.86
www.ualberta.ca is an alias for web1.srv.ualberta.ca.
www.ualberta.ca is an alias for web1.srv.ualberta.ca.

This is with glibc-2.8.90-4 and nscd NOT running.  In strace
I can notice:
....
futex(0x7f7570e77020, FUTEX_WAKE_PRIVATE, 1) = 1
rt_sigaction(SIGHUP, {0x7f75720dee23, ~[RTMIN RT_1], SA_RESTORER, 0x7f7571a7a110}, NULL, 8) = 0
rt_sigsuspend([])                       = ? ERESTARTNOHAND (To be restarted)
--- SIGTERM (Terminated) @ 0 (0) ---
rt_sigreturn(0xf)                       = -1 EINTR (Interrupted system call)
....

which seems to be related to the above.

With glibc-2.7-2 (F8) or glibc-2.6-4 (F7) I do not see that "stutter".

Just for a change 'host clock.redhat.com' responds with

clock.redhat.com has address 66.187.224.4
clock.redhat.com has address 66.187.233.4

in all three cases with a reverse query on that address bringing
'clock2.redhat.com'.

   Michal




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