[dns-operations] weird queries for mx1.mx2.mx1.mx2...

[Petr Špaček]

Hello everyone,

while debugging some resolution problems we have notices really weird queries, seemingly related to e-mail delivery. This is query list for domain truckinsurancekentucky.com:

mx1.mx1.mx1.mx1.mx1.mx2.mx1.mx2.mx1.mta-sts.mx1.mx1.mx2.mx2.mta-sts.mx1.mx1.truckinsurancekentucky.com. AAAA

mx1.mx1.mx1.mx2.mx1.mx2.mx1.mx2.mx2.mx1.mx1.mx1.mx2.mx2.mx2.mx1.mx2.mx2.truckinsurancekentucky.com. A

mx1.mx2.mx1.mx1.mx1.mx1.mx1.mx2.mx1.mx1.mta-sts.mx1.mx2.mx2.mx2.mx1.truckinsurancekentucky.com. A

mx1.mx2.mx1.mx1.mx2.mx1.mx1.mx2.mx1.mx1.mx1.mx1.mx2.mx1.mx2.mta-sts.mx1.truckinsurancekentucky.com. NS

mx1.mx2.mx1.mx2.mx2.mx1.mx1.mx1.mx1.mx2.mta-sts.mx1.mx1.mx2.mta-sts.mx2.mx2.truckinsurancekentucky.com. AAAA

mx1.mx2.mx2.mx1.mx2.mx2.mx1.mx2.mx2.mx2.mx2.mx1.mx2.mx1.mx2.mx1.mx1.mx1.truckinsurancekentucky.com. A

mx2.mx1.mx1.mx2.mx1.mx1.mx1.mx2.mx2.mx2.mx2.mta-sts.mx1.mx2.mta-sts.mx1.mx2.mx1.truckinsurancekentucky.com. NS

mx2.mx1.mx2.mx1.mx1.mx2.mx1.mx2.mx1.mx2.mx1.mx1.mx1.mx1.mta-sts.mx1.mx2.mx2.truckinsurancekentucky.com. NS

mx2.mx2.mx1.mx1.mx1.mx2.mx2.mx2.mx1.mx2.mx1.mx1.mx1.mta-sts.mx1.mx2.truckinsurancekentucky.com. A

mx2.mx2.mx1.mx1.mx2.mx1.mx2.mx1.mx1.mta-sts.mx1.mx2.mx1.mx1.mta-sts.mx2.mx2.truckinsurancekentucky.com. AAAA

mx2.mx2.mx1.mx2.mx1.mx1.mx1.mx2.mx1.mx1.mx1.mx1.mx1.truckinsurancekentucky.com. AAAA

mx2.mx2.mx1.mx2.mx1.mx1.mx1.mx2.mx2.mx2.mx1.mx1.mx1.mta-sts.mx1.mx2.mx2.mx2.truckinsurancekentucky.com. A

Domain truckinsurancekentucky.com is not the only one with this weird behavior. Does anyone have an idea what is causing this?

(We have access only to anonymized data so we are unable to pinpoint responsible client.)

-- 
Petr Špaček  @  CZ.NIC