Re: DNS not resolving for a particular domain only
In message <93595848.2099571.1503336849...@mail.yahoo.com>, U Zee writes: > Thanks Mark, > So mysteriously the problem is now gone and I have no idea how, I know > that I didn't change anything. > While investigating, I tried looking but didn't get anything in packet > capture on the recursive server, I think mainly because I had to grep for > something otherwise there was just too much traffic. So its possible, my > grep for lenovo didn't show related packets But I will never know now A single missing routing entry could have taken the site down. The delegation for lnvcdn.net only has 2 of the 4 nameservers listed and those 2 are in the same /24. There is a reason that it is recommended that there are multiple nameservers which are geographically and topologically dispersed are used and that both sides of the delegation have consistent NS and address records. It reduces the probability that single faults cause failures like this. Mark ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7439 ;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 6, ADDITIONAL: 3 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags: do; udp: 4096 ;; QUESTION SECTION: ;lnvcdn.net.IN NS ;; AUTHORITY SECTION: lnvcdn.net. 172800 IN NS ns1.lnvcdn.net. lnvcdn.net. 172800 IN NS ns2.lnvcdn.net. A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN NSEC3 1 1 0 - A1RUUFFJKCT2Q54P78F8EJGJ8JBK7I8B NS SOA RRSIG DNSKEY NSEC3PARAM A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN RRSIG NSEC3 8 2 86400 20170825051539 20170818040539 57899 net. ZbkC2I24NO+y91E+sPWOADqbjsVpHfuFhnox5QfeuImFsL2z0x3X+UG6 Lt9emQ23VFesgs8+J1WQVjHHBuhvc1XdWG7jBpv3Tr776oBcSF5rrqMp zC5CjRIzOlojSVpNG3snkW0xfijBuOl51RzaKrSqKb2x/tcXWUWkHpDw ga8= 2K5T76ECDUK1RJEDVHKHNL0LCCENKMES.net. 86400 IN NSEC3 1 1 0 - 2K673TEK531CUGB8J9QHASJNDFOVU87L NS DS RRSIG 2K5T76ECDUK1RJEDVHKHNL0LCCENKMES.net. 86400 IN RRSIG NSEC3 8 2 86400 20170828050756 20170821035756 57899 net. s905nQwEBRv9cbVzZMWFLfb0Jnq/K+R32MJdnYa9CaPpJCtGIMzWkmPt yl7MKawRlhJE01n4ll4/4Grj3asVi5/LsrGSH7bjO9GkclWqsuxoeepl JrUh/UkZFw5qhnCvw1teWAPcZ6T93DBmq02c8UemFAYRrMO1ugbvHGQo QPw= ;; ADDITIONAL SECTION: ns1.lnvcdn.net. 172800 IN A 192.16.0.5 ns2.lnvcdn.net. 172800 IN A 192.16.0.6 ;; Query time: 257 msec ;; SERVER: 2001:503:d414::30#53(2001:503:d414::30) ;; WHEN: Tue Aug 22 09:45:04 AEST 2017 ;; MSG SIZE rcvd: 592 ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22513 ;; flags: qr aa; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 5 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags: do; udp: 4096 ;; QUESTION SECTION: ;lnvcdn.net.IN NS ;; ANSWER SECTION: lnvcdn.net. 3600IN NS ns1.lnvcdn.net. lnvcdn.net. 3600IN NS ns3.lnvcdn.net. lnvcdn.net. 3600IN NS ns4.lnvcdn.net. lnvcdn.net. 3600IN NS ns2.lnvcdn.net. ;; ADDITIONAL SECTION: ns1.lnvcdn.net. 3600IN A 192.16.0.5 ns2.lnvcdn.net. 3600IN A 192.16.0.6 ns3.lnvcdn.net. 3600IN A 198.7.30.5 ns4.lnvcdn.net. 3600IN A 198.7.30.6 ;; Query time: 12 msec ;; SERVER: 192.16.0.5#53(192.16.0.5) ;; WHEN: Tue Aug 22 09:45:04 AEST 2017 ;; MSG SIZE rcvd: 175 > From: Mark Andrews > To: U Zee > Cc: Grant Taylor ; "bind-users@lists.isc.org" > > Sent: Monday, August 14, 2017 3:00 AM > Subject: Re: DNS not resolving for a particular domain only > > > In message <1396839156.197734.1502489970...@mail.yahoo.com>, U Zee via > bind-users writ > es: > > Thanks for the suggestion Grant. > > Here's what I get for the recursive server's capture: ( I queried from > > the recursive server itself from another ssh session so it is the client > > as well) > > > > # tcpdump -v -v -nt -i eth0 udp port 53|grep lenovotcpdump: listening on > > eth0, link-type EN10MB (Ethernet), capture size 65535 bytes  > >  86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ > A? www.lenovo.com. (32) > >  86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ > A? www.lenovo.com. (32) > >  86.36.AA.BB.36143 > 193.108.91.79.domain: [bad udp cksum c63c!] > 12966 [1au] A? > > www.lenovo.com. ar: . OPT UDPsize=4096 OK (43) > >  193.108.91.79.domain > 86.36.AA.BB.36143: [udp sum ok] 12966*- q: A? > www.lenovo.com. 1/0/1 www.lenovo.com. CNAME cs47.can.lnvcdn.net. ar: . > OPT UDPsize=4096 OK (76) > >  86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ > A? www.lenovo.com. (32) > >  86.36.AA.BB.10224 > 86.36.DD.EE.domain: [b
Re: DNS not resolving for a particular domain only
Thanks Mark, So mysteriously the problem is now gone and I have no idea how, I know that I didn't change anything. While investigating, I tried looking but didn't get anything in packet capture on the recursive server, I think mainly because I had to grep for something otherwise there was just too much traffic. So its possible, my grep for lenovo didn't show related packets But I will never know now From: Mark Andrews To: U Zee Cc: Grant Taylor ; "bind-users@lists.isc.org" Sent: Monday, August 14, 2017 3:00 AM Subject: Re: DNS not resolving for a particular domain only In message <1396839156.197734.1502489970...@mail.yahoo.com>, U Zee via bind-users writ es: > Thanks for the suggestion Grant. > Here's what I get for the recursive server's capture: ( I queried from > the recursive server itself from another ssh session so it is the client > as well) > > # tcpdump -v -v -nt -i eth0 udp port 53|grep lenovotcpdump: listening on > eth0, link-type EN10MB (Ethernet), capture size 65535 bytes > 86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ A? >www.lenovo.com. (32) > 86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ A? >www.lenovo.com. (32) > 86.36.AA.BB.36143 > 193.108.91.79.domain: [bad udp cksum c63c!] 12966 >[1au] A? > www.lenovo.com. ar: . OPT UDPsize=4096 OK (43) > 193.108.91.79.domain > 86.36.AA.BB.36143: [udp sum ok] 12966*- q: A? >www.lenovo.com. 1/0/1 www.lenovo.com. CNAME cs47.can.lnvcdn.net. ar: . OPT >UDPsize=4096 OK (76) > 86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ A? >www.lenovo.com. (32) > 86.36.AA.BB.10224 > 86.36.DD.EE.domain: [badudp cksum 18c7!] 12721 [1au] >A? www.lenovo.com.ourdomain.com. ar: . OPT UDPsize=4096 OK (57) > 86.36.DD.EE.domain > 86.36.AA.BB.10224: [udp sum ok] 12721 NXDomain*- q: >A? www.lenovo.com.ourdomain.com. 0/1/1 ns: ourdomain.com. SOA >master.ourdomain.com. host-master.ourparentdomain.com. 138524105 900 450 >360 60 ar: . OPT UDPsize=4096 OK (138) > 86.36.AA.CC.domain > 86.36.AA.BB.45776: [udp sum ok] 34468 ServFail q: A? >www.lenovo.com. 0/0/0 (32) > > 86.36.AA.BB = localhost (our recursive server) where I ran the query and > capture > 86.36.AA.CC = our secondary recursive server (no idea why that was > contacted) > 86.36.DD.EE = our one of two anycast addresses which point to the > recursive servers > > > So it looks like we do get to the CNAME (4th line) but still it > fails...?I also tried a capture from a regular linux client but the > output was similar except that it didn't include the CNAME line. Well the next stage is to trace what happens when the recursive server looks for cs47.can.lnvcdn.net, the target of the CNAME. Mark -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
Re: DNS not resolving for a particular domain only
In message <1396839156.197734.1502489970...@mail.yahoo.com>, U Zee via bind-users writ es: > Thanks for the suggestion Grant. > Here's what I get for the recursive server's capture: ( I queried from > the recursive server itself from another ssh session so it is the client > as well) > > # tcpdump -v -v -nt -i eth0 udp port 53|grep lenovotcpdump: listening on > eth0, link-type EN10MB (Ethernet), capture size 65535 bytes  >86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ A? > www.lenovo.com. (32) >86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ A? > www.lenovo.com. (32) >86.36.AA.BB.36143 > 193.108.91.79.domain: [bad udp cksum c63c!] 12966 > [1au] A? > www.lenovo.com. ar: . OPT UDPsize=4096 OK (43) >193.108.91.79.domain > 86.36.AA.BB.36143: [udp sum ok] 12966*- q: A? > www.lenovo.com. 1/0/1 www.lenovo.com. CNAME cs47.can.lnvcdn.net. ar: . OPT > UDPsize=4096 OK (76) >  86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ A? > www.lenovo.com. (32) >86.36.AA.BB.10224 > 86.36.DD.EE.domain: [badudp cksum 18c7!] 12721 [1au] > A? www.lenovo.com.ourdomain.com. ar: . OPT UDPsize=4096 OK (57) >86.36.DD.EE.domain > 86.36.AA.BB.10224: [udp sum ok] 12721 NXDomain*- q: > A? www.lenovo.com.ourdomain.com. 0/1/1 ns: ourdomain.com. SOA > master.ourdomain.com. host-master.ourparentdomain.com. 138524105 900 450 > 360 60 ar: . OPT UDPsize=4096 OK (138)  >86.36.AA.CC.domain > 86.36.AA.BB.45776: [udp sum ok] 34468 ServFail q: A? > www.lenovo.com. 0/0/0 (32) > > 86.36.AA.BB = localhost (our recursive server) where I ran the query and > capture > 86.36.AA.CC = our secondary recursive server (no idea why that was > contacted) > 86.36.DD.EE = our one of two anycast addresses which point to the > recursive servers > > > So it looks like we do get to the CNAME (4th line) but still it > fails...?I also tried a capture from a regular linux client but the > output was similar except that it didn't include the CNAME line. Well the next stage is to trace what happens when the recursive server looks for cs47.can.lnvcdn.net, the target of the CNAME. Mark -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
Re: DNS not resolving for a particular domain only
Thanks for the suggestion Grant. Here's what I get for the recursive server's capture: ( I queried from the recursive server itself from another ssh session so it is the client as well) # tcpdump -v -v -nt -i eth0 udp port 53|grep lenovotcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ A? www.lenovo.com. (32) 86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ A? www.lenovo.com. (32) 86.36.AA.BB.36143 > 193.108.91.79.domain: [bad udp cksum c63c!] 12966 [1au] A? www.lenovo.com. ar: . OPT UDPsize=4096 OK (43) 193.108.91.79.domain > 86.36.AA.BB.36143: [udp sum ok] 12966*- q: A? www.lenovo.com. 1/0/1 www.lenovo.com. CNAME cs47.can.lnvcdn.net. ar: . OPT UDPsize=4096 OK (76) 86.36.AA.BB.45776 > 86.36.AA.CC.domain: [bad udp cksum 8a1b!] 34468+ A? www.lenovo.com. (32) 86.36.AA.BB.10224 > 86.36.DD.EE.domain: [bad udp cksum 18c7!] 12721 [1au] A? www.lenovo.com.ourdomain.com. ar: . OPT UDPsize=4096 OK (57) 86.36.DD.EE.domain > 86.36.AA.BB.10224: [udp sum ok] 12721 NXDomain*- q: A? www.lenovo.com.ourdomain.com. 0/1/1 ns: ourdomain.com. SOA master.ourdomain.com. host-master.ourparentdomain.com. 138524105 900 450 360 60 ar: . OPT UDPsize=4096 OK (138) 86.36.AA.CC.domain > 86.36.AA.BB.45776: [udp sum ok] 34468 ServFail q: A? www.lenovo.com. 0/0/0 (32) 86.36.AA.BB = localhost (our recursive server) where I ran the query and capture 86.36.AA.CC = our secondary recursive server (no idea why that was contacted) 86.36.DD.EE = our one of two anycast addresses which point to the recursive servers So it looks like we do get to the CNAME (4th line) but still it fails...?I also tried a capture from a regular linux client but the output was similar except that it didn't include the CNAME line. Frankly I have no idea if this is giving any useful info. I did see that for other queries also I saw bad udp cksum messages so not sure if thats an actual problem. Do you see anything specific that might help us diagnose further? Thanks From: Grant Taylor via bind-users To: bind-users@lists.isc.org Sent: Friday, August 11, 2017 7:06 PM Subject: Re: DNS not resolving for a particular domain only On 08/11/2017 06:49 AM, U Zee via bind-users wrote: > Any ideas please??? I'm seeing different A records returned depending on where I query from. As such I can only speculate that something related to DNS for a CDN is not working as desired. I'd suggest a packet capture of the client's DNS traffic and possibly (if not likely) the client's recursive DNS server's traffic (related to the query.) -- Grant. . . . unix || die ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
Re: DNS not resolving for a particular domain only
On 08/11/2017 06:49 AM, U Zee via bind-users wrote: Any ideas please??? I'm seeing different A records returned depending on where I query from. As such I can only speculate that something related to DNS for a CDN is not working as desired. I'd suggest a packet capture of the client's DNS traffic and possibly (if not likely) the client's recursive DNS server's traffic (related to the query.) -- Grant. . . . unix || die smime.p7s Description: S/MIME Cryptographic Signature ___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
