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[gjarboni <jmitchel@xxxxxxxxxx>]

> The same issue is described here:
> http://www.unchartedbackwaters.co.uk/pyblosxom/debian_ubuntu_dns_resolution_delays
>
> I can confirm that removing mdns4 makes the problem go away. So it's
> really https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/94940,
> please merge.
>
> --
There are actually two bugs -- the mDNS bug that you described and the
fact that ping is doing a DNS lookup before sending each packet. I don't
know of another operating system that does this. Usually they do one
lookup before pinging, then none while pinging. Doing a ping before every
packet is my mind is just silly.

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https://bugs.launchpad.net/bugs/737959

Title:
  ping waits 5 seconds between packets if RDNS is not present

Status in iputils package in Ubuntu:
  Confirmed

Bug description:
  If you use ping from the command line and the host you are pinging
  does not have a rDNS entry, then ping pauses for 5 seconds or more
  between packets. Since there's no output on the terminal it looks as
  if the host is down, but when you press Ctrl-C, you get a line about
  the first packet.

  Here's the output from ping as well as a packet capture. b.b.b.b
  doesn't have an rDNS entry, but c.c.c.c does.

  a.a.a.a = my ip address
  b.b.b.b = pinged.machine.com
  c.c.c.c = 2nd.pinged.machine.com
  d.d.d.d = first dns server in resolv.conf

  21:56:10.348040 IP a.a.a.a.35806 > d.d.d.d.domain: 19049+ A? pinged.machine.com. (39)
  21:56:10.359921 IP d.d.d.d.domain > a.a.a.a.35806: 19049* 1/0/0 A[|domain]
  21:56:10.401162 IP a.a.a.a.35806 > d.d.d.d.domain: 10575+ PTR? b.b.b.b.in-addr.arpa. (44)
  21:56:10.413424 IP d.d.d.d.domain > a.a.a.a.35806: 10575 NXDomain 0/1/0 (121)
  21:56:15.497545 IP a.a.a.a.35806 > d.d.d.d.domain: 60024+ PTR? b.b.b.b.in-addr.arpa. (44)
  21:56:15.509826 IP d.d.d.d.domain > a.a.a.a.35806: 60024 NXDomain 0/1/0 (121)
  21:56:20.588606 IP a.a.a.a.35806 > d.d.d.d.domain: 28660+ PTR? b.b.b.b.in-addr.arpa. (44)
  21:56:20.624358 IP d.d.d.d.domain > a.a.a.a.35806: 28660 NXDomain 0/1/0 (121)
  21:56:25.671853 IP a.a.a.a.35806 > d.d.d.d.domain: 63426+ PTR? b.b.b.b.in-addr.arpa. (44)
  21:56:25.684198 IP d.d.d.d.domain > a.a.a.a.35806: 63426 NXDomain 0/1/0 (121)

  me@me-desktop:~/Desktop$ ping pinged.machine.com
  PING pinged.machine.com (b.b.b.b) 56(84) bytes of data.
  64 bytes from b.b.b.b: icmp_seq=1 ttl=124 time=41.0 ms
  64 bytes from b.b.b.b: icmp_seq=2 ttl=124 time=81.0 ms
  64 bytes from b.b.b.b: icmp_seq=3 ttl=124 time=76.1 ms
  64 bytes from b.b.b.b: icmp_seq=4 ttl=124 time=43.3 ms

  --- pinged.machine.com ping statistics ---
  4 packets transmitted, 4 received, 0% packet loss, time 15268ms
  rtt min/avg/max/mdev = 41.009/60.377/81.041/18.299 ms
  me@me-desktop:~/Desktop$ 

  22:15:38.966121 IP a.a.a.a.35806 > d.d.d.d.domain: 61313+ A? 2nd.machine.pinged.com. (42)
  22:15:38.966447 IP a.a.a.a.35807 > d.d.d.d.domain: 44215+ PTR? b.b.b.b.in-addr.arpa. (43)
  22:15:38.978502 IP d.d.d.d.domain > a.a.a.a.35806: 61313* 1/0/0 (58)
  22:15:38.980133 IP d.d.d.d.domain > a.a.a.a.35807: 44215 NXDomain* 0/1/0 (127)
  22:15:38.995406 IP a.a.a.a.35808 > d.d.d.d.domain: 45092+ PTR? c.c.c.c.in-addr.arpa. (43)
  22:15:39.017572 IP d.d.d.d.domain > a.a.a.a.35808: 45092* 1/0/0 (81)
  22:15:39.991054 IP a.a.a.a.35808 > d.d.d.d.domain: 48973+ PTR? c.c.c.c.in-addr.arpa. (43)
  22:15:40.002881 IP d.d.d.d.domain > a.a.a.a.35808: 48973* 1/0/0 (81)
  22:15:40.998392 IP a.a.a.a.35808 > d.d.d.d.domain: 78+ PTR? c.c.c.c.in-addr.arpa. (43)
  22:15:41.010430 IP d.d.d.d.domain > a.a.a.a.35808: 78* 1/0/0 (81)
  22:15:41.988781 IP a.a.a.a.35808 > d.d.d.d.domain: 21736+ PTR? c.c.c.c.in-addr.arpa. (43)
  22:15:42.000789 IP d.d.d.d.domain > a.a.a.a.35808: 21736* 1/0/0 (81)
  22:15:42.996923 IP a.a.a.a.35808 > d.d.d.d.domain: 43427+ PTR? c.c.c.c.in-addr.arpa. (43)
  22:15:43.009297 IP d.d.d.d.domain > a.a.a.a.35808: 43427* 1/0/0 (81)
  22:15:43.984441 IP a.a.a.a.35808 > d.d.d.d.domain: 59199+ PTR? a.a.a.a.in-addr.arpa. (41)
  22:15:43.997827 IP a.a.a.a.35809 > d.d.d.d.domain: 23386+ PTR? c.c.c.c.in-addr.arpa. (43)
  22:15:44.009554 IP d.d.d.d.domain > a.a.a.a.35809: 23386* 1/0/0 (81)
  22:15:44.036071 IP d.d.d.d.domain > a.a.a.a.35808: 59199 NXDomain*- 0/1/0 (118)
  22:15:44.990557 IP a.a.a.a.35809 > d.d.d.d.domain: 51955+ PTR? c.c.c.c.in-addr.arpa. (43)
  22:15:45.002374 IP d.d.d.d.domain > a.a.a.a.35809: 51955* 1/0/0 (81)

  me@me-desktop:~/Desktop$ ping 2nd.machine.pinged.com
  PING 2nd.machine.pinged.com (c.c.c.c) 56(84) bytes of data.
  64 bytes from 2nd.machine.pinged.com (c.c.c.c): icmp_seq=1 ttl=127 time=12.1 ms
  64 bytes from 2nd.machine.pinged.com (c.c.c.c): icmp_seq=2 ttl=127 time=18.7 ms
  64 bytes from 2nd.machine.pinged.com (c.c.c.c): icmp_seq=3 ttl=127 time=18.3 ms
  64 bytes from 2nd.machine.pinged.com (c.c.c.c): icmp_seq=4 ttl=127 time=21.9 ms
  64 bytes from 2nd.machine.pinged.com (c.c.c.c): icmp_seq=5 ttl=127 time=12.3 ms
  64 bytes from 2nd.machine.pinged.com (c.c.c.c): icmp_seq=6 ttl=127 time=11.8 ms
  64 bytes from 2nd.machine.pinged.com (c.c.c.c): icmp_seq=7 ttl=127 time=16.2 ms

  
  --- 2nd.machine.pinged.com ping statistics ---
  8 packets transmitted, 8 received, 0% packet loss, time 7018ms
  rtt min/avg/max/mdev = 11.894/16.067/21.995/3.431 ms
  me@me-desktop:~/Desktop$

  ProblemType: Bug
  DistroRelease: Ubuntu 10.04
  Package: iputils-ping 3:20071127-2ubuntu1
  ProcVersionSignature: Ubuntu 2.6.32-27.49-generic-pae 2.6.32.26+drm33.12
  Uname: Linux 2.6.32-27-generic-pae i686
  NonfreeKernelModules: nvidia
  Architecture: i386
  Date: Fri Mar 18 21:50:08 2011
  ProcEnviron:
   PATH=(custom, user)
   LANG=en_US.utf8
   SHELL=/bin/bash
  SourcePackage: iputils

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