Forum Discussion

gbam_190768's avatar
gbam_190768
Icon for Cirrus rankCirrus
Jun 21, 2016

Can you set an ephemeral node (FQDN) to an MX record?

I would to have an ephemeral node resolve an MX record. There is no A record associated. The F5 fails to resolve the node currently but I can successfully resolve it to the same DNS server if I ask ...
application delivery
BIG-IP Access Policy Manager (APM)
LTM
Chris_Grant's avatar
Chris_Grant
Icon for Employee rankEmployee
Jun 21, 2016

No, this won't work. When you are asking for an MX record, you are saying "What is the hostname for the mail server that services this domain name". It returns a value, which is mapped to an IP address as normal. So if you say "Give me the MX record for internal.f5.com" It might return "inmail.f5.com", but inmail.f5.com would map to an IP via a regular A record. So in my fictional example, it might look like this:

internal.f5.com
     MX 10 inmail.f5.com

inmail.f5.com IN A 1.2.3.4

internal.f5.com in this example has no A record, but inmail.f5.com does. So the MX lookup for internal.f5.com would eventually return 1.2.3.4, which is the IP associated with inmail.f5.com.

So you couldn't use the MX as the FQDN for an ephemeral node.