Recently I implemented Lync Online with a customer that had a lot of custom domain names. Adding the required DNS records manually would literary take hours, but luckily the customer used Windows DNS both internally and externally, so it was easy for me to write a script to add these DNS records.

In my case both DNS servers (internal and external) are running Windows Server 2008 R2. That gives me the option to use dnscmd.exe to add the records. Here is the script I used to add the records. Please note that you may need to modify the script if you are using subdomains.

#Get all domains registered in Office 365
Import-Module MSOnline
Connect-MsolService
$domains = Get-MsolDomain | Where-Object { $_.Name -notlike '*.onmicrosoft.com' }
$dnsserver = 'srv-dns01'

#Loop through all domains and add the required DNS records for all domains
foreach ($domain in $domains) {
    Write-Verbose "Adding records for domain $($domain.Name)"
    &"dnscmd.exe $dnsserver /RecordAdd $($domain.Name) sip CNAME sipdir.online.lync.com"
    &"dnscmd.exe $dnsserver /RecordAdd $($domain.Name) lyncdiscover CNAME webdir.online.lync.com"
    &"dnscmd.exe $dnsserver /RecordAdd $($domain.Name) _sipfederationtls._tcp SRV 100 1 5061 sipfed.online.lync.com."
    &"dnscmd.exe $dnsserver /RecordAdd $($domain.Name) _sip._tls SRV 100 1 443 sipdir.online.lync.com."
} 

Now I reduced this time-consuming (and boring) task to just a few minutes!

/ Andreas