How to setup Office 365 without moving your DNS to Microsoft…

Posted by in Exchange, Lync, Office 365

I’ve recently setup a simple Office 365 deployment but instead of buckling to Microsoft and moving the DNS to their servers I wanted to set it up using my existing registrar for the DNS. The GUI at Office 365 doesn’t exactly make this crystal clear so I thought I’d show the steps involved in sorting it out.

First, you need to add the custom domain to Office 365 and verify that you own it.

  1. On the Admin page, under Domains, click Add a domain.
  2. Type your domain and click Next.
  3. Go through the steps in order to verify your domain. The easiest way to do it is with a TXT record. They’ll give you a TXT record to register in your domain’s DNS that can be looked up by Microsoft to verify you own the domain.
  4. Once you’ve added in the TXT record (or used an MX record if that’s what you decided to do) then click the Verify button. Depending on your DNS hosting provider, publication of the TXT record can take anything from a few minutes to 72 hours (although a few hours is most likely).
  5. If everything was entered okay, your domain will be verified. Now, click Cancel. Your domain will remain verified but you will not proceed to the part where you update your DNS name servers to be the Microsoft ones.
  6. How you need to enter the correct DNS for your domain at your own DNS hosting provider. The list of DNS entries needed for Exchange Online and Lync Online are as follows (the custom domain name I’m using in the example below is
Type Priority Host Name Points to… TTL
MX 0 @ 1 Hour
CNAME N/A autodiscover 1 Hour
CNAME N/A sip 1 Hour
CNAME N/A lyncdiscover 1 Hour


Type TXT Name TXT Value TTL
TXT @ v=spf1 ~all 1 Hour


Type Service Protocol Port Weight Priority TTL Name Target
SRV _sipfederationtls _tcp 5061 1 100 1 Hour
SRV _sip _tls 443 1 100 1 Hour


Easy peasy.