DNS records for Skype online
External DNS records required for Skype for Business Online
| DNS record | Purpose | Value to use |
| SRV (Skype for Business Online) | Allows your Office 365 domain to share instant messaging (IM) features with external clients by enabling SIP federation. | Service: _sipfederationtls Protocol: _TCP Priority: 100 Weight: 1 Port: 5061 Target: Sipfed.online.lync.com |
| SRV (Skype for Business Online) | Used by Skype for Business to coordinate the flow of information between Lync clients. | Service: _sip Protocol: _TLS Priority: 100 Weight: 1 Port: 443 Target: sipdir.online.lync.com |
| CNAME (Skype for Business Online) | Used by the Lync client to help find the Skype for Business Online service and sign in. | Alias: sip Target: sipdir.online.lync.com |
| CNAME (Skype for Business Online) | Used by the Lync mobile client to help find the Skype for Business Online service and sign in. | Alias: lyncdiscover Target: webdir.online.lync.com |