dns latency
Bob Harold
rharolde at umich.edu
Fri Apr 12 16:52:00 UTC 2019
On Fri, Apr 12, 2019 at 12:37 PM Paul A <razor at meganet.net> wrote:
> Mark, per my previous email, this high latency only happens when digging
> for
> Comcast. I did not compile bind on this machine, I'm using the latest Bind
> package that came with CentOS 7, bind-chroot-9.9.4-73.el7_6.x86_64. Looking
> at the changelog for the RPM it doesn't mention any issue with dig and
> latency and I assume this has been patched by Redhat at some point.
>
> I just wanted to verify that what Im seeing with Comcast is somehow not
> related to only me and someone else is seeing this issue. The lastest dig
> I
> did came back with
> "dig: couldn't get address for 'dns101.comcast.net': no more" so I doubt
> it's a dig version issue.
>
> Paul
>
>
> ;; Received 239 bytes from 192.5.6.30#53(192.5.6.30) in 32 ms
>
> net. 172800 IN NS k.gtld-servers.net.
> net. 172800 IN NS b.gtld-servers.net.
> net. 172800 IN NS l.gtld-servers.net.
> net. 172800 IN NS a.gtld-servers.net.
> net. 172800 IN NS m.gtld-servers.net.
> net. 172800 IN NS c.gtld-servers.net.
> net. 172800 IN NS i.gtld-servers.net.
> net. 172800 IN NS e.gtld-servers.net.
> net. 172800 IN NS d.gtld-servers.net.
> net. 172800 IN NS g.gtld-servers.net.
> net. 172800 IN NS h.gtld-servers.net.
> net. 172800 IN NS j.gtld-servers.net.
> net. 172800 IN NS f.gtld-servers.net.
> net. 86400 IN DS 35886 8 2
> 7862B27F5F516EBE196804
> 44D4CE5E762981931842C465F00236401D 8BD973EE
> net. 86400 IN RRSIG DS 8 1 86400 20190425050000
> 2019
> 0412040000 25266 . Uk5bsrr1dgoBFUYfzSYTi6D+QXow1CZglnE3BUZ7I/I0HjuywiSf2YLx
> eU1c
> rjlYOJQdYPxDFQIH5/aItTtrM7wgvTOhfhHPHQuAj2f8ovYIlwCt
> hguq+9jcNTMAzrUXvi6Tb8oTb36
> lprYIfg21yO1d8RO6cx3L0dJMcuez
> WN2kxNAg+wrx+dWbOexFO7Hs0gzDPpsMx0lEOkJHcfyb/V71An
> MV+nob 48G/azRzQ2fJfs849OyYmjTXA88bAcxxz3kNCoddOfWuMU+WKV5Lfy7J
> NkegEfRCzRZYYKiD
> MwI0zURTg+CdZAYKuxvJQW9ddzSiK5UnYXZVSO1d fPXfYQ==
> ;; Received 1168 bytes from 199.9.14.201#53(b.root-servers.net) in 88 ms
>
> comcast.net. 172800 IN NS dns101.comcast.net.
> comcast.net. 172800 IN NS dns102.comcast.net.
> comcast.net. 172800 IN NS dns103.comcast.net.
> comcast.net. 172800 IN NS dns104.comcast.net.
> comcast.net. 172800 IN NS dns105.comcast.net.
> comcast.net. 86400 IN DS 40909 5 2
> 30C0F50E68DCC9A2F279A9
> 94C07CF22CED97AADF44C2B1FE38A1B32B A1A34174
> comcast.net. 86400 IN DS 40909 5 1
> DDC19733884EE533B35B4B
> 57717BEA9B0EF2C4D1
> comcast.net. 86400 IN RRSIG DS 8 2 86400
> 20190417054136
> 2019
> 0410043136 51638 net.
> l2Vj2W+qzAziqzcC+Y+t4+6b6ADTwyILCzbySVmj5mj5J9vscR4mYf+f X
> zNGKen73GecLw+HiwwSzUG8jYkGtvNOMrj9ZbC4v+XWuq0EFcxDEhbJ
> yTAq2wPMGD6evSUSDLfqYu8h
> oJH9svqS06KlBjWkKQqx8X+ZIIqmUMVk ivk=
> dig: couldn't get address for 'dns101.comcast.net': no more
>
> -----Original Message-----
> From: Mark Andrews [mailto:marka at isc.org]
> Sent: Friday, April 12, 2019 11:20 AM
> To: Paul A <razor at meganet.net>
> Cc: bind-users at lists.isc.org <bind-users at isc.org>
> Subject: Re: dns latency
>
> Before you pay attention to the round trip time you need this fix from BIND
> 9.9.6 from nearly 5 years ago now (2014-07-31).
>
> 3903. [bug] Improve the accuracy of DiG's reported round trip
> time. [RT 36611]
>
> Mark
>
> > On 13 Apr 2019, at 12:59 am, Paul A <razor at meganet.net> wrote:
> >
> > This is not really a Bind issue, but can anyone else confirm latency
> > when querying Comcast from the root down? I ask because this morning
> some
> of our customers Could not email @comcast addresses, looked at the mail
> server and domain not found. I suspect my cache for Comcast timeout and
> when
> my DNS server tried doing a new query it timeout on GTLD server to Comcast?
> >
> > When I query directly to their DNS servers there is no latency, so I
> suspect this is a link issue at Comcast affecting DNS?
> >
> > TIA paul
> >
> >
> >
> > ; <<>> DiG 9.9.4-RedHat-9.9.4-61.el7_5.1 <<>> @192.5.6.30 comcast.net
> > -t a +trace ; (1 server found) ;; global options: +cmd
> > . 518400 IN NS i.root-servers.net.
> > . 518400 IN NS j.root-servers.net.
> > . 518400 IN NS k.root-servers.net.
> > . 518400 IN NS l.root-servers.net.
> > . 518400 IN NS m.root-servers.net.
> > . 518400 IN NS a.root-servers.net.
> > . 518400 IN NS b.root-servers.net.
> > . 518400 IN NS c.root-servers.net.
> > . 518400 IN NS d.root-servers.net.
> > . 518400 IN NS e.root-servers.net.
> > . 518400 IN NS f.root-servers.net.
> > . 518400 IN NS g.root-servers.net.
> > . 518400 IN NS h.root-servers.net.
> > ;; Received 239 bytes from 192.5.6.30#53(192.5.6.30) in 32 ms
> >
> > net. 172800 IN NS a.gtld-servers.net.
> > net. 172800 IN NS b.gtld-servers.net.
> > net. 172800 IN NS c.gtld-servers.net.
> > net. 172800 IN NS d.gtld-servers.net.
> > net. 172800 IN NS e.gtld-servers.net.
> > net. 172800 IN NS f.gtld-servers.net.
> > net. 172800 IN NS g.gtld-servers.net.
> > net. 172800 IN NS h.gtld-servers.net.
> > net. 172800 IN NS i.gtld-servers.net.
> > net. 172800 IN NS j.gtld-servers.net.
> > net. 172800 IN NS k.gtld-servers.net.
> > net. 172800 IN NS l.gtld-servers.net.
> > net. 172800 IN NS m.gtld-servers.net.
> > net. 86400 IN DS 35886 8 2
> 7862B27F5F516EBE19680444D4CE5E762981931842C465F00236401D 8BD973EE
> > net. 86400 IN RRSIG DS 8 1 86400
> 20190425050000 20190412040000 25266 .
> Uk5bsrr1dgoBFUYfzSYTi6D+QXow1CZglnE3BUZ7I/I0HjuywiSf2YLx
> eU1crjlYOJQdYPxDFQIH5/aItTtrM7wgvTOhfhHPHQuAj2f8ovYIlwCt
> hguq+9jcNTMAzrUXvi6Tb8oTb36lprYIfg21yO1d8RO6cx3L0dJMcuez
> WN2kxNAg+wrx+dWbOexFO7Hs0gzDPpsMx0lEOkJHcfyb/V71AnMV+nob
> 48G/azRzQ2fJfs849OyYmjTXA88bAcxxz3kNCoddOfWuMU+WKV5Lfy7J
> NkegEfRCzRZYYKiDMwI0zURTg+CdZAYKuxvJQW9ddzSiK5UnYXZVSO1d fPXfYQ==
> > ;; Received 1168 bytes from 198.97.190.53#53(h.root-servers.net) in 19
> > ms
> >
> > comcast.net. 172800 IN NS dns101.comcast.net.
> > comcast.net. 172800 IN NS dns102.comcast.net.
> > comcast.net. 172800 IN NS dns103.comcast.net.
> > comcast.net. 172800 IN NS dns104.comcast.net.
> > comcast.net. 172800 IN NS dns105.comcast.net.
> > comcast.net. 86400 IN DS 40909 5 2
> 30C0F50E68DCC9A2F279A994C07CF22CED97AADF44C2B1FE38A1B32B A1A34174
> > comcast.net. 86400 IN DS 40909 5 1
> DDC19733884EE533B35B4B57717BEA9B0EF2C4D1
> > comcast.net. 86400 IN RRSIG DS 8 2 86400
> 20190417054136 20190410043136 51638 net.
> l2Vj2W+qzAziqzcC+Y+t4+6b6ADTwyILCzbySVmj5mj5J9vscR4mYf+f
> XzNGKen73GecLw+HiwwSzUG8jYkGtvNOMrj9ZbC4v+XWuq0EFcxDEhbJ
> yTAq2wPMGD6evSUSDLfqYu8hoJH9svqS06KlBjWkKQqx8X+ZIIqmUMVk ivk=
> > ;; Received 612 bytes from 192.42.93.30#53(g.gtld-servers.net) in
> > 25090 ms
> >
> > comcast.net. 30 IN A 69.252.80.75
> > comcast.net. 30 IN RRSIG A 5 2 30 20190418174157
> 20190411143657 26550 comcast.net.
> YegwZlzjBoJ+b9nWTHwRZQbce619UcOVdo6FUPG056Sod4MEchv/GCHu
> 7BpREAUm0CBoE4qbipTiS47wIk7QJYzz10B78wRgMGNwMTUXQ571YRyq
> P0I3I0Dzag28j607walJOZms3lAXDzSnyvv9wocaH2MJ7Z3j68Qf5pKh YpM=
> > ;; Received 227 bytes from 69.252.250.103#53(dns101.comcast.net) in 14
> > ms
> >
> > _______________________________________________
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>
> --
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742 INTERNET: marka at isc.org
>
>
I get 57ms max for the various gtld servers. Could you try this:
for x in a b c d e f g h i j k l m; do echo "==== $x ===="; dig comcast.net.
+norec +noall +auth +stats @$x.gtld-servers.net.; done
--
Bob Harold
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