DNS Records required to use Lync Online (Office 365) with a Vanity Domain

Note - this only applies if you have your own "vanity domain" such as companyname.com. This does not apply if you are using the Microsoft Online domains "onmicrosoft.com"

I've seen quite a few people asking for help with this, and struggled a little bit when I first set this up myself, so I thought I would post the DNS entries that are required to get Lync Online working.

These are generic DNS records, so it doesn't matter what server / service you have.

Now, first off you will need to get yourself a relatively advanced DNS Management Service. I personally use the most excellent Zone Edit (www.zoneedit.com). This is completely free and allows you a very high level of control over what records you can create. I have found with some of the other DNS management sites that sometimes you cannot create some of the required records (such as SRV records).
DNS Records described by Office 365 Portal

There is 1 SRV record and 2 CNAME records that you need to create.

You can find these in your Office 365 Portal under "Domains" and "verify DNS Settings". Below is the screenshot from my own Portal Site for my domain "hatchsolutions.co.uk".

The thing to note is that it gives you the full host-name entry for each of the records you need to create. When you actually create these (depending on your DNS management tool) you will probably only need the prefix for the host name.

So the three records you need to create are:

• _sipfederationtls
• Type: SRV
• Port: 5061
• Weight: 1
• Priority: 100
• TTL: 3600 (seconds)
• Target: sipfed.online.lync.com
• sip
• Type: CNAME
• TTL: 3600 (seconds)
• Host-Name: sipdir.online.lync.com
• lyncdiscover
• Type: CNAME
• TTL: 3600 (seconds)
• Host-Name: webdir.online.lync.com

So you can see above, I have only used the initial part of the full hostname. Having a CNAME record called "sip" in my managed domain "hatchsolutions.co.uk" gives me the fully-qualified address "sip.hatchsolutions.co.uk".

But ... that's not all ...

I also found in my environment that one more SRV record was required, which for some reason was missing from the official instructions. I honestly can't remember where I found this (credit goes to someone wonderful person on the blogosphere somewhere) but the details are below:

• _sip._tls
• Type: SRV
• Port: 443
• Weight: 1
• Priority: 100
• TTL: 3600 (seconds)
• Target: sipdir.online.lync.com

I found that once that is also in place, everything started working. You may need to wait for 24 hours (for this to propogate round the world's DNS servers) and you should be good to go! (I think I had to wait a good few hours before mine started working .. so please be patient!)