DNS Error: 6396909 DNS type 'mx' lookup of ece.uprm.edu responded with code SERVFAIL

[DLD]

Hi.

Somebody users using email hosted in google mail servers try to send an e-mail to my domain and they receive  the following error.

DNS type 'mx' lookup of ece.uprm.edu responded with code SERVFAIL

 

This only happen with some google users accounts, others can send emails to my domain without problems .Thanks for your help.

[Alex Dupuy]

The Google Public DNS resolvers in the Netherlands are not getting responses from your on-campus name servers in AS 5786 (dns1.uprm.edu, dns2.uprm.edu, dns1.ece.uprm.edu, and dns2.ece.uprm.edu, all in the 136.145.0.0/16 netblock). This is responsible for the Gmail issues you are seeing; any Gmail user whose Gmail servers are located in that data center would have difficulties sending you mail. Note that since your MX records point to MTAs in the same netblock, fixing the DNS problem (as noted below) won't solve your e-mail problem, since Gmail servers in the Netherlands won't be able to make SMTP connections to your MTAs either. You might want to consider adding a lower priority holding/forwarding MTA for your domain on another network to prevent problems with e-mail bouncing as a result of network issues.

As noted in the domain checking tool results https://zonemaster.net/result/657921a8445210c5 and https://zonalizer.makeinstall.se/?FmNMeTFiSeWpBsW1uJxxiw, all of your name servers for ece.uprm.edu are in the same AS number, and this means that routing glitches (like the one in the Netherlands) can make your domain entirely inaccessible.

The parent uprm.edu domain has a third name server (dns2.azure.uprm.edu) presumably running in the Azure cloud, and you might want to check with the UPRM IT department to see if that name server can act as a secondary for the ece.uprm.edu zone (instead of, or in addition to, the dns1.uprm.edu secondary). You could also see about getting secondary DNS from upr1.upr.edu, which has an IPv6 address (although if UPRM is IPv4 only it isn't so critical). If you do add or replace name servers for ece.uprm.edu, make sure to update the NS records not only in the ece.uprm.edu zone, but also in the parent uprm.edu zone, or Google Public DNS, which only uses the name server names from the parent, won't see any reliability improvement from your new secondary DNS.

Compare with the results for uprm.edu at https://zonemaster.net/result/1c2e13c034360c68 and https://zonalizer.makeinstall.se/?uRYJPr4ZSU6TLzvQzB_2Yw, which have no warnings in the connectivity section (the warnings about missing PTRs in the addresses section are not really important, and should be notices, not warnings).