Skype for Business DNS Error

Skype for Business DNS Error

Resolution 1: Individual Client

Click on the Gear in the upper right hand corner > Click on Tools > Options > Personal (on the left) > click Advanced button near the user id > choose Manual Configuration >

Internal Server Name: sipdir.online.lync.com:443
External Server Name: sipdir.online.lync.com:443

Resolution 2: Entire Organization

Go to your DNS server

Create CNAME alias
  Alias name: lyncdiscover
  FQDN: lyncdiscover.yourdomain.com
  FQD for target host: webdir.online.lync.com

Create CNAME alias
  Alias name: sip
  FQDN: sip.yourdomain.com
  FQD for target host: sipdir.online.lync.com

Create Other Record > Service Location (SRV) Resource Record (may already be created)
Domain: yourdomain.com
Service: _sip
Protocal: _tls
Priority: 100
Weight: 1
Port number: 443
Host offering this service: sipdir.online.lync.com

To verify this go to DNS > expand domain > look at the "_tcp" folder and then look for the sipfed.online.lync.com record.

Go to the client machine and run "ipconfig /flushdns" and also verify the DNS server that he is using to authenticate against.

Below are the DNS records required for Skype for business online

SRV records

Type	Service	Protocol	Port	Weight	Priority	TTL	Name	Target
SRV	_sip	_tls	443	1	100	1 hour	Domain.com	sipdir.online.lync.com
SRV	_sipfederationtls	_tcp	5061	1	100	1 hour	Domain.com	sipfed.online.lync.com

CNAME for Lync Desktop client Autodiscover

Type	Host name	Destination	TTL
CNAME	sip.yourDomainName.com	sipdir.online.lync.com	1 hour

CNAME for Lync Mobile client Autodiscover

Type	Host name	Destination	TTL
CNAME	lyncdiscover.yourDomainName.com	webdir.online.lync.com	1 hour

Reference articles.

Setup Skype for business online.

https://support.office.com/en-us/article/Set-up-Skype-for-Business-Online-40296968-e779-4259-980b-c2de1c044c6e?ui=en-US&rs=en-US&ad=US

Skype for business network requirements.

https://support.microsoft.com/en-in/kb/2566790