One or more of the following features don't work as expected in Skype for Business Online (formerly Lync Online):
Skype for Business Online Autodiscover and automatic sign-in
Skype for Business Online federation with external users
Public Internet Connectivity (PIC) together with Windows Live, MSN, and Outlook.com users
Outlook Web Access instant messaging
Sign in from Lync Mobile clients by using the Auto-Detect Server option
Or, you receive one of the following error messages when you sign in to Lync 2010 or Lync 2013:
Lync couldn’t find a Lync Server for contoso.com. There might be an issue with the Domain Name System (DNS) configuration for your domain. Please contact your support team.
Cannot sign in because the server is temporarily unavailable. If the problem continues, please contact your support team.
To resolve these issues, make sure that you add the following service (SRV) and alias (CNAME) records to your Domain Name System (DNS) host.
Note The <DomainName> placeholder in this table represents the name of the Session Initiation Protocol (SIP) domain of your organization, such as contoso.com.
This issue occurs if all the following conditions are true:
You use a custom domain in Office 365.
DNS SRV resource records, CNAME resource records, or both kinds of records are configured incorrectly for your domain.
Troubleshoot Skype for Business Online DNS issues with the Lync Remote Connectivity Analyzer (RCA)
Go to the Lync Connectivity Analyzer and select Office 365 Custom/Vanity Domain Name Settings Test for Lync. Enter the sign-in address that you're using when you to try to sign in to Skype for Business Online (for example, email@example.com), and start the test.
This test examines all four DNS records that are required by Skype for Business Online to determine whether they're correctly configured.
If any issues are detected, check the DNS configuration with your domain registrar. For instructions about how to configure DNS for the most common DNS providers, go to the following Microsoft Office 365 website:
If you can't add SRV records through your DNS host
Some DNS hosts can't host SRV records, or the DNS hosts don't have options to host SRV records. This condition blocks the ability to communicate with external users (Federated and PIC). In these cases, there is currently no workaround except to change DNS hosts or to manage DNS through an on-premises DNS host.
Some UNIX or Linux OS servers that host DNS don’t require the underscore (_) when you add SRV records to the DNS host. If your DNS host is running UNIX or Linux and the SRV records aren’t resolving correctly, remove the underscore from the host name of the SRV record.
For more information about how to create and verify DNS SRV records if you have an on-premises DNS host, go to the following Microsoft TechNet website: