See below the DNS records that need to be added to your internet facing zone to consume Office 365 services such as email, Skype For Business and MDM.
The example below is for.. you guessed it: example.com
; Zone file for Office 365 services – please append the data below to your zone file
@ 3600 IN MX 0 example-com.mail.protection.outlook.com.
autodiscover 3600 IN CNAME autodiscover.outlook.com.
sip 3600 IN CNAME sipdir.online.lync.com.
lyncdiscover 3600 IN CNAME webdir.online.lync.com.
enterpriseregistration 3600 IN CNAME enterpriseregistration.windows.net.
enterpriseenrollment 3600 IN CNAME enterpriseenrollment.manage.microsoft.com.
@ 3600 IN TXT “v=spf1 include:spf.protection.outlook.com -all”
_sip._tls.example.com. 3600 IN SRV 100 1 443 sipdir.online.lync.com.
_sipfederationtls._tcp.example.com. 3600 IN SRV 100 1 5061 sipfed.online.lync.com.
Note that we no longer need the msoid CNAME record.
To validate your DNS records, use free online validators such as the ones at DNSToolBox or validate via the admin portal in Office 365.