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Found a subdomain sipdir.online.lync.com which is not resolved probably unavailable or deprecated, I found a domain during security testing which has a dangling CNAME of this particular domain unresolvable since that particular domain configured it's CNAME record as this domain. To prove the security vulnerability I need to claim the ownership of this sipdir.online.lync.com. I request concerned admin or authorities to confirm the ownership of this domain sipdir.online.lync.com and it's availability.
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You could refer to this for latest URL and IP address to release for Microsoft 365 service:
All the subdomains of *.lync.com belongs to microsoft teams?
All the subdomains of *.lync.com belongs to Microsoft Team?
The subdomains of *.lync.com are generally associated with Microsoft services, specifically with Microsoft Lync, which has been rebranded as Skype for Business. Since Microsoft Teams is part of the same suite of Office 365 tools that includes Skype for Business, some of these subdomains might be used in relation to Teams, especially during the transition period from Skype for Business to Teams. However, it's important to note that Microsoft Teams has its own set of domains and subdomains primarily under *.teams.microsoft.com.
May I know the current ownership of sipdir.online.lync.com which is inactive and configured as CNAME record of some other company's domain name. It could help me to create a vulnerability report to that client on dangling CNAME record to Subdomain takeover if I can able to create or host any static page on that..