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Exchange 2013: Significance of LegacyExchangeDN

LegacyExchangeDN attribute has been playing a great part in Exchange and outlook communication. This has given some NDRs if user was recreated. Exchange 2013 has come up with some changes so let us go through the changes and whats new here.

Active Directory does indexing of LegacyExchangeDn attribute but it can’t go beyond 126 bytes. So we need to make only 1st 126 bytes unique then rest. If we copy over 126bytes size LegacyExchangeDN to ProxyAddresses, active directory query degrades the performance.

This is why Exchange 2013 adds a guid before the alias of the user. This is a default behaviour and not a bug.

Legdnew

We can turn off this behavior by running the below cmd. I could not run this command from my CU3 server but this command is looking possible in the future release as this is mentioned in the technet and configuration.

Set-OrganizationConfig -IsGuidPrefixedLegacyDnDisabled $true

legdn

Reference Link: http://technet.microsoft.com/en-us/library/aa997443(v=exchg.150).aspx

I have logged a bug at Microsoft so I will update here if this bug gets resolved.

 

Prabhat Nigam

Microsoft MVP | Exchange Server

Team@MSExchangeGuru

5 Responses to “Exchange 2013: Significance of LegacyExchangeDN”

  1. suresh Says:

    Good to know about LegacyExchangeDN change in E2K13, could you please help me describe this statement more, appreciate your help.

    Active Directory does indexing of LegacyExchangeDn attribute but it can’t go beyond 126 bytes. So we need to make only 1st 126 bytes unique then rest. If we copy over 126bytes size LegacyExchangeDN to ProxyAddresses, active directory query degrades the performance.

  2. Prabhat Nigam Says:

    @Suresh
    AD Performance degrade means delayed response to the queries and more utilization of hardware.

    This link might help if you are facing any AD issue. http://technet.microsoft.com/en-us/library/cc961826.aspx

  3. suresh Says:

    I wanted to understand this part

    Active Directory does indexing of LegacyExchangeDn attribute but it can’t go beyond 126 bytes. So we need to make only 1st 126 bytes unique then rest. If we copy over 126bytes size LegacyExchangeDN to ProxyAddresses

  4. John Says:

    FYI, that parameter is for Office 365/Internal Microsoft.

    “This parameter is reserved for internal Microsoft use.”

  5. Prabhat Nigam Says:

    @John
    I hope the blog was helpful to you which is the purpose of the blog.

    Let me tell you, I have asked the same question to the product group. Being an MVP we get the access to discuss the issues with product group.
    Product group had asked me to open the bug so bug number 3428 is open with Microsoft developer team. I am still waiting to hear back from them.

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