Thus said Chris Smith on Fri, 06 Dec 2013 11:31:23 -0500: > Basically, four of my networks are not getting an answer for a > specific mx query from dyn.com's DNS server. Yet every other DNS cache > I've queried works just fine (Google, Level3, Hurricane Electric, > Comcast, etc.) and dyn's support claims there is no problem on their > end and all of their tests return the proper answer just as one of my > networks does.
Seems dyn might be doing a transparent load balancing proxy for their DNS; what else could account for the strange TTL jumping around below? Perhaps they have a bad server in the pool that you just happen to hit consistently due to some hashing. Notice the first query is 3600 (normal given that is the TTL). The second query shows it took me 3 seconds to issue the query again. But the third shows a sudden jump in time of almost 5 minutes. $ env DNSCACHEIP=216.146.35.35 dnsqr mx lwtitle.com 15 lwtitle.com: 133 bytes, 1+1+2+0 records, response, noerror query: 15 lwtitle.com answer: lwtitle.com 3600 MX 0 lwtitle-com.mail.protection.outlook.com authority: lwtitle.com 3600 NS ns22.domaincontrol.com authority: lwtitle.com 3600 NS ns21.domaincontrol.com $ env DNSCACHEIP=216.146.35.35 dnsqr mx lwtitle.com 15 lwtitle.com: 133 bytes, 1+1+2+0 records, response, noerror query: 15 lwtitle.com answer: lwtitle.com 3597 MX 0 lwtitle-com.mail.protection.outlook.com authority: lwtitle.com 3597 NS ns22.domaincontrol.com authority: lwtitle.com 3597 NS ns21.domaincontrol.com $ env DNSCACHEIP=216.146.35.35 dnsqr mx lwtitle.com 15 lwtitle.com: 133 bytes, 1+1+2+0 records, response, noerror query: 15 lwtitle.com answer: lwtitle.com 3350 MX 0 lwtitle-com.mail.protection.outlook.com authority: lwtitle.com 3350 NS ns22.domaincontrol.com authority: lwtitle.com 3350 NS ns21.domaincontrol.com Then a few more seconds passed and I see: $ env DNSCACHEIP=216.146.35.35 dnsqr mx lwtitle.com 15 lwtitle.com: 133 bytes, 1+1+2+0 records, response, noerror query: 15 lwtitle.com answer: lwtitle.com 3095 MX 0 lwtitle-com.mail.protection.outlook.com authority: lwtitle.com 3095 NS ns22.domaincontrol.com authority: lwtitle.com 3095 NS ns21.domaincontrol.com $ env DNSCACHEIP=216.146.35.35 dnsqr mx lwtitle.com 15 lwtitle.com: 133 bytes, 1+1+2+0 records, response, noerror query: 15 lwtitle.com answer: lwtitle.com 3331 MX 0 lwtitle-com.mail.protection.outlook.com authority: lwtitle.com 3331 NS ns22.domaincontrol.com authority: lwtitle.com 3331 NS ns21.domaincontrol.com Has anything changed recently with the NS records for lwtitle.com? Do you get the same results if you query one of the other well known public DNS resolvers like 8.8.8.8? Andy -- TAI64 timestamp: 4000000052a25f91
