On 1/6/16 15:08, Kevin Kretz wrote:
> Whether the responses to the query work properly in the browsers is a
> different issue. There's nothing inherently wrong with multiple and
> different responses to queries in different subnets or regions.
>
True. But I'm trying to figure out why do the answers differ so much,
when from my side everything is on the same subnet, announced as
84.205.252.0/23 on our BGP. I would expect all of them to end up on the
same google anycast cluster and receive the same answer (or nearly the
same).
Sot.
> ------------------------------------------------------------------------
> *From: *"Sotiris Tsimbonis" <sts...@forthnet.gr>
> *To: *"Kevin Kretz" <ke...@rentec.com>
> *Cc: *bind-us...@isc.org
> *Sent: *Wednesday, June 1, 2016 7:46:38 AM
> *Subject: *Re: different answers from google's authoritative servers
>
> On 1/6/16 14:41, Kevin Kretz wrote:
>> Sotiris,
>>
>> There could be multiple A records for load balancing.
>>
>
> Of course, but answers of the first and second servers are on the same
> subnet, and more importantly, work on the users' browsers.
>
> The third set of answers is on a completely different subnet and
> produces ssl errors in the browsers.. Like if it's a cluster for another
> service, region or whatever..
>
> Sot.
>
>> ------------------------------------------------------------------------
>> *From: *"Sotiris Tsimbonis" <sts...@forthnet.gr>
>> *To: *bind-us...@isc.org
>> *Sent: *Wednesday, June 1, 2016 7:34:00 AM
>> *Subject: *different answers from google's authoritative servers
>>
>> Hi all,
>>
>> We have 3 recursive resolvers on the same subnet, and one of them is
>> getting different answers for the same things from google's
>> authoritative dns servers.
>>
>> [root@syz3ns01 ~]# RESOLVERS="ns1.google.com. ns2.google.com.
>> ns3.google.com. ns4.google.com."
>> [root@syz3ns01 ~]# SITES="www.google.com. www.google.gr."
>> [root@syz3ns01 ~]# for resolver in ${RESOLVERS} ; do for site in
>> ${SITES}; do echo "${resolver} ${site} $(dig +short A ${site}
>> @${resolver})" ; done ; done
>> ns1.google.com. www.google.com. 216.58.211.4
>> ns1.google.com. www.google.gr. 216.58.211.3
>> ns2.google.com. www.google.com. 216.58.211.4
>> ns2.google.com. www.google.gr. 216.58.211.3
>> ns3.google.com. www.google.com. 216.58.211.4
>> ns3.google.com. www.google.gr. 216.58.211.3
>> ns4.google.com. www.google.com. 216.58.211.4
>> ns4.google.com. www.google.gr. 216.58.211.3
>>
>> [root@syz3ns02 ~]# RESOLVERS="ns1.google.com. ns2.google.com.
>> ns3.google.com. ns4.google.com."
>> [root@syz3ns02 ~]# SITES="www.google.com. www.google.gr."
>> [root@syz3ns02 ~]# for resolver in ${RESOLVERS} ; do for site in
>> ${SITES}; do echo "${resolver} ${site} $(dig +short A ${site}
>> @${resolver})" ; done ; done
>> ns1.google.com. www.google.com. 216.58.211.36
>> ns1.google.com. www.google.gr. 216.58.211.35
>> ns2.google.com. www.google.com. 216.58.211.36
>> ns2.google.com. www.google.gr. 216.58.211.35
>> ns3.google.com. www.google.com. 216.58.211.36
>> ns3.google.com. www.google.gr. 216.58.211.35
>> ns4.google.com. www.google.com. 216.58.211.36
>> ns4.google.com. www.google.gr. 216.58.211.35
>>
>> [root@syz3ns03 ~]# RESOLVERS="ns1.google.com. ns2.google.com.
>> ns3.google.com. ns4.google.com."
>> [root@syz3ns03 ~]# SITES="www.google.com. www.google.gr."
>> [root@syz3ns03 ~]# for resolver in ${RESOLVERS} ; do for site in
>> ${SITES}; do echo "${resolver} ${site} $(dig +short A ${site}
>> @${resolver})" ; done ; done
>> ns1.google.com. www.google.com. 172.217.16.36
>> ns1.google.com. www.google.gr. 172.217.16.35
>> ns2.google.com. www.google.com. 172.217.16.36
>> ns2.google.com. www.google.gr. 172.217.16.35
>> ns3.google.com. www.google.com. 172.217.16.36
>> ns3.google.com. www.google.gr. 172.217.16.35
>> ns4.google.com. www.google.com. 172.217.16.36
>> ns4.google.com. www.google.gr. 172.217.16.35
>>
>> The IP addresses of our servers are 84.205.252.16, 84.205.252.18 and
>> 84.205.252.20 respectively.
>>
>> The problem with the third answer set is on the users' browsers, it
>> produces an ssl certificate error and users cannot access google.
>>
>> traceroute to google's dns servers are different on the penultimate hop
>> (hop 12)
>>
>> [root@syz3ns01 ~]# traceroute ns3.google.com.
>> traceroute to ns3.google.com (216.239.36.10), 30 hops max, 38 byte packets
>> 1 syz3fw01-dmz.servers.n3.syzefxis.gov.gr (10.95.1.1) 0.405 ms 0.262
>> ms 0.217 ms
>> 2 84.205.252.6 (84.205.252.6) 0.718 ms 0.504 ms 0.511 ms
>> 3 193.92.42.169 (193.92.42.169) 0.937 ms 1.024 ms 0.482 ms
>> 4 194.219.208.29 (194.219.208.29) 1.017 ms 1.004 ms 0.946 ms
>> MPLS Label=757472 CoS=5 TTL=1 S=0
>> 5 xe-0-3-1.core-lsf-08.forthnet.gr (213.16.247.193) 0.950 ms 1.063
>> ms 0.982 ms
>> 6 74.125.48.74 (74.125.48.74) 8.373 ms 8.374 ms 8.341 ms
>> 7 72.14.237.27 (72.14.237.27) 8.352 ms 72.14.237.189 (72.14.237.189)
>> 12.085 ms 72.14.237.27 (72.14.237.27) 8.979 ms
>> 8 209.85.253.114 (209.85.253.114) 26.920 ms 26.114 ms 25.789 ms
>> MPLS Label=772454 CoS=5 TTL=1 S=0
>> 9 216.239.58.8 (216.239.58.8) 50.816 ms 209.85.241.233
>> (209.85.241.233) 42.159 ms 43.461 ms
>> MPLS Label=756878 CoS=5 TTL=1 S=0
>> 10 209.85.251.178 (209.85.251.178) 45.549 ms 44.474 ms 45.682 ms
>> MPLS Label=720256 CoS=5 TTL=1 S=0
>> 11 74.125.37.103 (74.125.37.103) 39.998 ms 216.239.49.244
>> (216.239.49.244) 48.116 ms 74.125.37.150 (74.125.37.150) 42.865 ms
>> MPLS Label=25186 CoS=5 TTL=1 S=0
>> 12 209.85.251.231 (209.85.251.231) 39.575 ms 72.14.238.43
>> (72.14.238.43) 43.933 ms 209.85.242.165 (209.85.242.165) 46.748 ms
>> 13 * *Icmp checksum is wrong
>> *
>> 14 ns3.google.com (216.239.36.10) 41.453 ms 39.987 ms 47.545 ms
>> [root@syz3ns01 ~]#
>>
>> [root@syz3ns02 ~]# traceroute ns3.google.com.
>> traceroute to ns3.google.com (216.239.36.10), 30 hops max, 38 byte packets
>> 1 syz3fw01-dmz.servers.n3.syzefxis.gov.gr (10.95.1.1) 0.232 ms 0.283
>> ms 0.209 ms
>> 2 84.205.252.6 (84.205.252.6) 0.688 ms 0.535 ms 0.455 ms
>> 3 193.92.42.169 (193.92.42.169) 1.715 ms 0.835 ms 0.726 ms
>> 4 194.219.208.29 (194.219.208.29) 1.248 ms 0.876 ms 0.773 ms
>> MPLS Label=757472 CoS=5 TTL=1 S=0
>> 5 xe-0-3-1.core-lsf-08.forthnet.gr (213.16.247.193) 0.755 ms 1.047
>> ms 0.944 ms
>> 6 74.125.48.74 (74.125.48.74) 8.331 ms 8.546 ms 8.328 ms
>> 7 72.14.237.189 (72.14.237.189) 12.286 ms 72.14.237.27 (72.14.237.27)
>> 5.935 ms 72.14.237.189 (72.14.237.189) 13.211 ms
>> 8 209.85.253.114 (209.85.253.114) 22.488 ms 209.85.240.160
>> (209.85.240.160) 25.713 ms 26.401 ms
>> MPLS Label=554255 CoS=5 TTL=1 S=0
>> 9 216.239.57.244 (216.239.57.244) 41.070 ms 209.85.241.233
>> (209.85.241.233) 34.822 ms 209.85.242.79 (209.85.242.79) 38.180 ms
>> MPLS Label=27780 CoS=5 TTL=1 S=0
>> 10 209.85.251.178 (209.85.251.178) 36.262 ms 66.249.95.39
>> (66.249.95.39) 44.744 ms 209.85.143.25 (209.85.143.25) 43.497 ms
>> MPLS Label=25688 CoS=5 TTL=1 S=0
>> 11 216.239.49.240 (216.239.49.240) 42.459 ms 216.239.49.244
>> (216.239.49.244) 42.738 ms 39.587 ms
>> MPLS Label=731306 CoS=5 TTL=1 S=0
>> 12 72.14.238.215 (72.14.238.215) 46.858 ms 216.239.51.147
>> (216.239.51.147) 48.715 ms 209.85.246.164 (209.85.246.164) 86.761 ms
>> Icmp checksum is wrong
>> 13 * * *
>> 14 ns3.google.com (216.239.36.10) 48.178 ms 48.106 ms 48.157 ms
>> [root@syz3ns02 ~]#
>>
>> [root@syz3ns03 ~]# traceroute ns3.google.com.
>> traceroute to ns3.google.com (216.239.36.10), 30 hops max, 38 byte packets
>> 1 syz3fw01-dmz.servers.n3.syzefxis.gov.gr (10.95.1.1) 0.297 ms 0.393
>> ms 0.447 ms
>> 2 84.205.252.6 (84.205.252.6) 0.454 ms 0.574 ms 0.751 ms
>> 3 193.92.42.169 (193.92.42.169) 0.938 ms 0.823 ms 0.733 ms
>> 4 194.219.208.29 (194.219.208.29) 1.260 ms 0.766 ms 1.267 ms
>> MPLS Label=757472 CoS=5 TTL=1 S=0
>> 5 xe-0-3-1.core-lsf-08.forthnet.gr (213.16.247.193) 15.388 ms 1.248
>> ms 1.446 ms
>> 6 74.125.48.74 (74.125.48.74) 5.410 ms 5.378 ms 5.435 ms
>> 7 72.14.237.27 (72.14.237.27) 12.224 ms 12.309 ms 72.14.237.189
>> (72.14.237.189) 5.354 ms
>> 8 209.85.240.160 (209.85.240.160) 22.422 ms 35.365 ms 22.601 ms
>> MPLS Label=536927 CoS=5 TTL=1 S=0
>> 9 216.239.57.244 (216.239.57.244) 43.196 ms 209.85.242.79
>> (209.85.242.79) 40.263 ms 216.239.57.244 (216.239.57.244) 43.387 ms
>> MPLS Label=27555 CoS=5 TTL=1 S=0
>> 10 209.85.251.178 (209.85.251.178) 41.581 ms 209.85.143.25
>> (209.85.143.25) 36.869 ms 66.249.95.39 (66.249.95.39) 44.804 ms
>> MPLS Label=24801 CoS=5 TTL=1 S=0
>> 11 216.239.49.244 (216.239.49.244) 44.189 ms 74.125.37.154
>> (74.125.37.154) 47.331 ms 216.239.49.244 (216.239.49.244) 48.582 ms
>> MPLS Label=549098 CoS=5 TTL=1 S=0
>> 12 209.85.246.135 (209.85.246.135) 47.964 ms 209.85.251.231
>> (209.85.251.231) 42.683 ms 72.14.238.215 (72.14.238.215) 43.525 ms
>> 13 * * *
>> 14 ns3.google.com (216.239.36.10) 49.559 ms 48.009 ms 48.148 ms
>> [root@syz3ns03 ~]#
>>
>> Any ideas please?
>> Sot.
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