Verify logged in user against exchange distribution list or AD groups in c#

I am trying to ver开发者_运维知识库ify whether the logged in user exists in a AD group or distribution list. I tried to use WindowsIdentity but that does not give me proper results. If I add a user to the DL and then check whether the user is in the DL, it gives me incorrect results.

I restarted my IIS and even cleared my browser cookies and cache, but no luck. Where does the IsInRole() function verifies for the user role. In AD or on local machine....? I tried to remove myself from local machine group too, but it still authorizes me for that group. Any help would be appreciated.

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If you are using .NET 3.5, you can consider to use Principal.IsMemberOf() in System.DirectoryServices.AccountManagement. I tried it and it works with AD security group as well as DL. More details about how to programming with groups can be found here