Subdomain records for microsoft exchange online

@daveb55d3c5c299

One issue that I spotted right off was the fact that you’re not defining the actual sub-domain anywhere in your DNS Zone.

An MX entry does not function as a zone entry for a sub-domain in terms of defining it as a usable point of entry. This entry simply tells the mail server where to point, but it doesn’t function as the base level for an actual sub-domain. You’d need to add either a CNAME for the sub-domain or an A entry (if using an IP).

If your DNS Zone is identical to what you’ve setup above, since subdomain doesn’t have a base entry from which to work from, calls to x.subdomain would not function since the base subdomain doesn’t actually exist in the zone file.

Ideally, you would want to setup the MX CNAME as mail or similar, simply for clarity. That’s how I’d set it up if I were doing the same. For example, I’d take the DNS Zone you provided above and modify it to:

MX		mail												subdomain-domain-ca.mail.protection.outlook.com
CNAME	subdomain											location.wherethesubdomainpoints.ext
CNAME	autodiscover.subdomain								autodiscover.outlook.com
CNAME	msoid.subdomain										clientconfig.microsoftonline-p.net
CNAME	enterpriseenrollment.subdomain						enterpriseenrollment.manage.microsoft.com
CNAME	enterpriseregistration.subdomain					enterpriseregistration.windows.net
CNAME	sip.subdomain										sipdir.online.lync.com
CNAME	lyncdiscover.subdomain								webdir.online.lync.com
TXT		v=spf1 include:spf.protection.outlook.com -all
SIP		sip.tls												sipdir.online.lync.com
SRV		sipfederationtls.tcp								sipfed.online.lync.com

The defining change is line #2 where the subdomain is actually defined.