Today will explain what are “Apex a records”
These are simply the “A records” we have for defining address of web hosting server but incase when we have NO mx records, they work like Apex a record. In those cases all incoming mails are delivered directly to web hosting server which hosting the domain.
Concept is not of much importance but sometimes crazy things happens like e.g for a domain.com mx records are mail-server.isp.net while A record points to web hosting server 1.2.3.4
Now if mx record, i.e which is actually a hostname mail-server.sip.net doesn’t resolves becuase of some error at dns hosting of isp, mails are delivered at web hosting server on ip – 1.2.3.4 which makes things crazy, either mails will be rejected or may be delivered on un-expected location.
I found many server admin still depend on apex a record for email delivery which isn’t a good idea. Best possible way for email hosting setup via an inhouse server is to create an mx record for in house server.
It requires two steps:
- create a hostname like – mail-server.your-domain.com and point it to ip of email hosting server.
- create mx record for your-domain.com pointing to mail-server.your-domain.com
That’s all required for inhouse email hosting setup. Sounds simple….right? 
