Teams connectivity issues due to missing DNS PTR records

%3CLINGO-SUB%20id%3D%22lingo-sub-1594917%22%20slang%3D%22en-US%22%3ETeams%20connectivity%20issues%20due%20to%20missing%20DNS%20PTR%20records%3C%2FLINGO-SUB%3E%3CLINGO-BODY%20id%3D%22lingo-body-1594917%22%20slang%3D%22en-US%22%3E%3CP%3EHi%20there%2C%3CBR%20%2F%3E%3CBR%20%2F%3EAll%20of%20the%20Internet%20traffic%20from%20my%20corporate%20LAN%20has%20to%20traverse%20a%20web%20proxy%2C%20including%20traffic%20to%20Teams.%20Our%20web%20proxies%20allow%20connections%20to%20all%20%3CSTRONG%3EURLs%3C%2FSTRONG%3E%20listed%20in%20the%20%E2%80%9COffice%20365%20URLs%20and%20IPs%E2%80%9D%20website%20but%20we%20can't%20have%20IP%20addresses%20in%20the%20web%20proxy%20allowed%20ACL.%3C%2FP%3E%3CP%3EWe%20have%20noticed%20that%20Teams%20P2P%20calls%20are%20intermittently%20failing%20and%20after%20investigation%20we%20have%20found%20that%20some%20of%20the%20IP%20addresses%20that%20Teams%20is%20trying%20to%20connect%20don't%20have%20a%20DNS%20PTR%20record.%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EThe%20web%20proxy%20whitelist%20validation%20does%20a%20DNS%20lookup%20when%20the%20connection%20is%20made%20to%20an%20IP%20address%20and%20if%20it%20can%20resolve%20a%20name%20for%20the%20IP%20address%2C%20it%20will%20check%20if%20that%20name%2FURL%20is%20in%20the%20whitelist%2C%20therefore%20allowing%20the%20connection.%20If%20the%20IP%20address%20can%E2%80%99t%20be%20resolved%20to%20a%20name%20then%20the%20connection%20is%20blocked%20because%20the%20web%20proxy%20can't%20validate%20if%20that%20is%20in%20the%20allowed%20list%20or%20not%20%3B)%3C%2Fimg%3E%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EUsing%20the%20Teams%20Network%20Assessment%20Tool%20(%3CA%20href%3D%22https%3A%2F%2Fdocs.microsoft.com%2Fen-us%2Fmicrosoftteams%2F3-envision-evaluate-my-environment%22%20target%3D%22_blank%22%20rel%3D%22noopener%20noopener%20noreferrer%20noopener%20noreferrer%20noopener%20noreferrer%20noopener%20noreferrer%20noopener%20noreferrer%20noopener%20noreferrer%20noopener%20noreferrer%20noopener%20noreferrer%22%3Ehttps%3A%2F%2Fdocs.microsoft.com%2Fen-us%2Fmicrosoftteams%2F3-envision-evaluate-my-environment%3C%2FA%3E)%20I%20can%20see%20that%20TCP%2FHTTPs%20connection%20fails%20against%204%20IP%20address%20ranges%20because%20those%20IPs%20don't%20have%20a%20PTR%20record%20-%20see%20details%20below%2C%20which%20is%20why%20Teams%20P2P%20calls%20are%20intermittently%20failing.%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EI%E2%80%99m%20fully%20aware%20that%20P2P%20calls%20should%20be%20using%20UDP%20traffic%20and%20I%E2%80%99m%20working%20with%20my%20network%20team%20to%20allow%20UDP%20traffic%20from%20all%20of%20the%20different%20subnets%20we%20have%2C%20but%20I%E2%80%99m%20also%20wondering%20what%20else%20might%20be%20intermittently%20failing%20given%20that%20Teams%20can%E2%80%99t%20successfully%20establish%20a%20TCP%2FHTTPs%20connection%20to%20those%20IP%20addresses%3F%20-%20See%20attached%20file%20for%20full%20result%20of%20the%20Connectivity%20Analyzer%20test%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EIs%20someone%20reading%20this%20message%20able%20to%20raise%20a%20request%20to%20have%20PTR%20records%20created%20for%20those%20IP%20ranges%2C%20so%20there%20is%20consistency%20on%20all%20addresses%20that%20are%20used%20by%20Teams%2C%20please%3F%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EThank%20you%2C%3C%2FP%3E%3CP%3EEduardo%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3E13.107.64.2%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%20world.tr.teams.microsoft.com%3C%2FP%3E%3CP%3E13.107.65.5%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%20eu.tr.teams.microsoft.com%3C%2FP%3E%3CP%3E52.113.192.2%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%20world52.tr.teams.microsoft.com%3C%2FP%3E%3CP%3E52.113.193.5%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%20eu52.tr.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.220.1%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%2052-114-220-1.relay.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.220.254%26nbsp%3B%2052-114-220-254.relay.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.221.1%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%2052-114-221-1.relay.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.221.254%26nbsp%3B%2052-114-221-254.relay.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.222.1%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%2052-114-222-1.relay.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.222.254%26nbsp%3B%2052-114-222-254.relay.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.223.1%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%2052-114-223-1.relay.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.223.254%26nbsp%3B%2052-114-223-254.relay.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.124.1%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%2052-114-124-1.relay.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.124.254%26nbsp%3B%2052-114-124-254.relay.teams.microsoft.com%3C%2FP%3E%3CP%3E52.114.125.1%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%26nbsp%3B%2052-114-125-1.relay.teams.microsoft.com%3C%2FP%3E%3CP%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Occasional Contributor

Hi there,

All of the Internet traffic from my corporate LAN has to traverse a web proxy, including traffic to Teams. Our web proxies allow connections to all URLs listed in the “Office 365 URLs and IPs” website but we can't have IP addresses in the web proxy allowed ACL.

We have noticed that Teams P2P calls are intermittently failing and after investigation we have found that some of the IP addresses that Teams is trying to connect don't have a DNS PTR record.

 

The web proxy whitelist validation does a DNS lookup when the connection is made to an IP address and if it can resolve a name for the IP address, it will check if that name/URL is in the whitelist, therefore allowing the connection. If the IP address can’t be resolved to a name then the connection is blocked because the web proxy can't validate if that is in the allowed list or not ;)

 

Using the Teams Network Assessment Tool (https://docs.microsoft.com/en-us/microsoftteams/3-envision-evaluate-my-environment) I can see that TCP/HTTPs connection fails against 4 IP address ranges because those IPs don't have a PTR record - see details below, which is why Teams P2P calls are intermittently failing.

 

I’m fully aware that P2P calls should be using UDP traffic and I’m working with my network team to allow UDP traffic from all of the different subnets we have, but I’m also wondering what else might be intermittently failing given that Teams can’t successfully establish a TCP/HTTPs connection to those IP addresses? - See attached file for full result of the Connectivity Analyzer test

 

Is someone reading this message able to raise a request to have PTR records created for those IP ranges, so there is consistency on all addresses that are used by Teams, please?

 

Thank you,

Eduardo

 

13.107.64.2        world.tr.teams.microsoft.com

13.107.65.5        eu.tr.teams.microsoft.com

52.113.192.2      world52.tr.teams.microsoft.com

52.113.193.5      eu52.tr.teams.microsoft.com

52.114.220.1      52-114-220-1.relay.teams.microsoft.com

52.114.220.254  52-114-220-254.relay.teams.microsoft.com

52.114.221.1      52-114-221-1.relay.teams.microsoft.com

52.114.221.254  52-114-221-254.relay.teams.microsoft.com

52.114.222.1      52-114-222-1.relay.teams.microsoft.com

52.114.222.254  52-114-222-254.relay.teams.microsoft.com

52.114.223.1      52-114-223-1.relay.teams.microsoft.com

52.114.223.254  52-114-223-254.relay.teams.microsoft.com

52.114.124.1      52-114-124-1.relay.teams.microsoft.com

52.114.124.254  52-114-124-254.relay.teams.microsoft.com

52.114.125.1      52-114-125-1.relay.teams.microsoft.com

52.114.125.254  52-114-125-254.relay.teams.microsoft.com

52.114.126.1      52-114-126-1.relay.teams.microsoft.com

52.114.126.254  52-114-126-254.relay.teams.microsoft.com

52.114.127.1      52-114-127-1.relay.teams.microsoft.com

52.114.127.254  52-114-127-254.relay.teams.microsoft.com

52.114.62.1        52-114-62-1.relay.teams.microsoft.com

52.114.62.254    52-114-62-254.relay.teams.microsoft.com

52.114.63.1        52-114-63-1.relay.teams.microsoft.com

52.114.63.254    52-114-63-254.relay.teams.microsoft.com

52.114.188.1      PTR doesn't exist

52.114.188.254  PTR doesn't exist

52.114.189.1      PTR doesn't exist

52.114.189.254  PTR doesn't exist

52.114.190.1      PTR doesn't exist

52.114.190.254  PTR doesn't exist

52.114.191.1      PTR doesn't exist

52.114.191.254  PTR doesn't exist

 

6 Replies
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Hi, 

Even if it is not recommended to use proxies for Teams traffic and if you anyway decides to use proxy you should reconsider that a couple if times. If you after reconsideration anyway decides to let Teams traffic go thru the proxy you should know that it probably will end up with problems, and think about it a couple of times extra.

 

So, nobody recommends Teams traffic to go thru a proxy. But the PTR records should be added, so that might help you a bit. Maybe @ThereseSolimeno can get this to the correct people?

52.114.188.1      PTR doesn't exist

52.114.188.254  PTR doesn't exist

52.114.189.1      PTR doesn't exist

52.114.189.254  PTR doesn't exist

52.114.190.1      PTR doesn't exist

52.114.190.254  PTR doesn't exist

52.114.191.1      PTR doesn't exist

52.114.191.254  PTR doesn't exist

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@ThereseSolimeno I see that an answer has been marked, does it mean you were able to get this to the right team?
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Yes @Eduardo Menezes   They will bug it.

 

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Thank you very much :)
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I talked to people in the product group yesterday about this so now they are aware. No ETA when it can be solved but I keep you updated when I hear anything.

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thank you very much Linus :)