For various reasons I won’t go into I’ve set up a custom DNS server for a delegated subdomain of my main domain. This DNS server is a .NET application which uses the ARSoft DNS library to respond to requests. This DNS server is working fine for A, CNAME and TXT records, but it doesn’t seem to respond to MX requests when they have been forwarded from other popular open DNS servers. NSLOOKUP responds with the message “google-public-dns-a.google.com can’t find cloud.xibis.net: Server failed” but if I use another DNS server like dns.xibis.com (the delegated subdomain DNS server) it works fine.
Here is a link to the output of the dig tool for the request:
(Click ‘Dig’ to proceed)
You can clearly see at the bottom of the trace output that my DNS server is responding with the MX records, but the Google DNS server won’t forward them for some reason.
The reason I’m doing this is to set up this domain for use with GSuite/Gmail.
Does anyone have any suggestions as to why this might be happening?