Are the DNS records for Skype for Business Online still required when in Teams Only?

[Forrest Hoffman]

Can someone answer if I can delete the old DNS entries?

Have been running Teams only mode since March 2020.

We have a few users with the PSTN from Microsoft as Add-On. One license is for Polycom Trio (voice only) running the Teams Client app in a Conference Room.

We use a lot of the Microsoft Conferencing Add-on as well.

I cannot determine from the MS docs if we still need the old DNS entries from running Skype for Business Online.  We never had On-Prem.

Can I delete these that MS is still listing in the Org Setup wizard of the Office Admin Portal

Skype for Business
CNAME	sip	sipdir.online.lync.com
CNAME	lyncdiscover	webdir.online.lync.com
SRV	_sip	sipdir.online.lync.com
SRV	_sipfederationtls	sipfed.online.lync.com

[#2]

According to MS docs: yes you do.
https://docs.microsoft.com/en-us/microsoft-365/enterprise/external-domain-name-system-records?view=o...

I know a lot of orgs don't and have not had problems but I've also had issues with some tenants where trying to create resource accounts is problematic if you don't have the _sipfederationtls SRV record.

My suggestion is that there's no harm in keeping them.

[#3]

I found those docs, And it clearly states for Skype for Business Online. I understand what you mean. I was just cleaning up and it seems strange to leave entries that reference Lync and Skype when those haven't been used for more than a year in our case. Even this doc has similarly obscure details
https://docs.microsoft.com/en-us/microsoft-365/admin/get-help-with-domains/create-dns-records-at-any...

[#4 · Accepted solution]

It does also say:

Note
These DNS records also apply to Teams, especially in a hybrid Teams and Skype for Business scenario, where certain federation issues could arise.

As I say, plenty of customers don't have them and never had a problem but others have when there's no SRV record. If you also have federated partners who use Skype for Business, then you'd need those records for them to federate with you.

[#5]

Is this still true?

`sipdir.online.lync.com` and `webdir.online.lync.com` are no longer resolving in dns, so i removed the `CNAME` and `SRV` entries pointing to them.

[#6]

I have the same question.

Whilst trying to update some other DNS records, my control panel is refusing to let me commit changes as these errors are now showing as faulty due to not resolving to A, AAAA or CNAME

[#7]

According to this article now, scroll down to the "External DNS records required for Teams" section, it now says that only the SRV _sipfederationtls._tcp record is needed. It points to sipfed.online.lync.com and that DOES still resolve.
https://learn.microsoft.com/en-us/microsoft-365/enterprise/external-domain-name-system-records

This article also seems to indicate to delete the CNAME sip and lyncdiscover records and _sip._tls SRV record, and leave only the _sipfederationtls._tcp SRV record.
https://learn.microsoft.com/en-us/SkypeForBusiness/hybrid/decommission-manage-dns-entries