How to Add the SRV Records for Lync Office 365 to Your Domain's DNS Records

I am in the process of switching from Google Apps to Office 365. I'll post more about my reasons, but for this post, I want to help you with one of the more difficult tasks in setting up Office 365: adding the correct records to your DNS zone file so that Lync will work with your domain.

The domain I use with Office 365 is williamrice.net. The administrative panel tells me to add these records to my domain's DNS zone file:

There's just one problem with that. My registrar, where I create these records, doesn't give me a user interface that has fields like Service, Protocol, Port, Weight, and Priority. My registrar assumes that if I'm modifying SRV records, I know what I'm doing. So they don't give me an easy, fill-in-the-blank interface for entering the SRV record. Fortunately, they do give me great technical support.

I sent my registrar the screenshot above, and they sent me the following lines to add to my zone file:

_sipfederationtls._tcp 3600 IN SRV 1 100 5061 sipfed.online.lync.com.

sip 3600 IN CNAME sipdir.online.lync.com. 

lyncdiscover 3600 IN CNAME webdir.online.lync.com.

Let me point out a few things about those lines. In the first line, notice that the Service and Protocol have been joined together, with a period between them. In each line, the TTL (Time To Live) setting of 1 Hour is written as 3600. And, each line ends with a period.

Let's translate the information that Microsoft gave me for the SRV record, into the line that my registrar gave me. Then you can make the same translation for your SRV record:

1. The record begins with the Service, _sipfederationtls.
2. Then, type a period (.).
3. Add the Protocol, _tcp.
4. Type a space.
5. Then the TTL, but instead of hours it is expressed in seconds, 3600.
6. Type a space.
7. Add IN.
8. Type a space.
9. Add the Type, SRV.
10. Type a space.
11. Add the Weight, 1.
12. Type a space.
13. Add the Priority, 100.
14. Type a space.
15. Add the Port, 5061.
16. Type a space.
17. Add the Target, sipfed.online.lync.com.
18. Type a period (.).

You're done. That's the line that you want to add for the SRV record, to enable Lync to work with your domain. Also, add the two CNAME records. Their format is much easier, and, your registrar probably has a fill-in-the-blank interface for adding CNAME records.

Remember to leave a comment if this is helpful (or not). I hope that Office 365 and Lync work as well for you as they have for me.