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Does Exchange 2016 support the .LAW TLD? RRS feed

  • Question

  • My customer has on-premise Exchange 2016 and is considering changing their domain name to use the ".LAW" TLD.  For example., the customer would like to add a new domain like CONTOSO.LAW to their existing Exchange 2016 system.

    Before attempting that, I thought it would be good to verify that Exchange 2016 supports that new TLD.  Can someone please either verify that ".LAW" is supported by Exchange 2016 and/or point me to the list of domains that Exchange 2016 does support?

    Thanks!

    Ken Morley


    Wednesday, December 18, 2019 2:24 PM

Answers

  • My customer has on-premise Exchange 2016 and is considering changing their domain name to use the ".LAW" TLD.  For example., the customer would like to add a new domain like CONTOSO.LAW to their existing Exchange 2016 system.

    Before attempting that, I thought it would be good to verify that Exchange 2016 supports that new TLD.  Can someone please either verify that ".LAW" is supported by Exchange 2016 and/or point me to the list of domains that Exchange 2016 does support?

    Thanks!

    Ken Morley


    There is no list of supported domains. If they are structurally valid, that's what matter ( this applies to 2016 as well)

    https://docs.microsoft.com/en-us/exchange/plan-and-deploy/system-requirements?view=exchserver-2019

    DNS namespace Exchange 2019 supports the following DNS namespaces:
    • Contiguous
    • Noncontiguous
    • Single label domains
    • Disjoint
    For more information about DNS namespaces that are supported by Exchange, see KB2269838.

    https://support.microsoft.com/en-us/help/2269838/microsoft-exchange-compatibility-with-single-label-domains-disjointed

    Ensure you meet these requirements in the last link and you will be fine.

    • Marked as answer by Andy DavidMVP Friday, December 20, 2019 12:26 PM
    Wednesday, December 18, 2019 8:32 PM
  • Hi Ken,

    As Andy mentioned, for internal domain names, any TLD can be used. Because this is used for internal organization and cannot be found from the Internet. If you want to use the TLD with Internet, you should make sure the TLD is valid and available from the list of top-level domains maintained by the IANA. Exchange doesn't have an additional TLD list.

    Regards,

    Lydia Zhou


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Thursday, December 19, 2019 2:52 AM

All replies

  • My customer has on-premise Exchange 2016 and is considering changing their domain name to use the ".LAW" TLD.  For example., the customer would like to add a new domain like CONTOSO.LAW to their existing Exchange 2016 system.

    Before attempting that, I thought it would be good to verify that Exchange 2016 supports that new TLD.  Can someone please either verify that ".LAW" is supported by Exchange 2016 and/or point me to the list of domains that Exchange 2016 does support?

    Thanks!

    Ken Morley


    There is no list of supported domains. If they are structurally valid, that's what matter ( this applies to 2016 as well)

    https://docs.microsoft.com/en-us/exchange/plan-and-deploy/system-requirements?view=exchserver-2019

    DNS namespace Exchange 2019 supports the following DNS namespaces:
    • Contiguous
    • Noncontiguous
    • Single label domains
    • Disjoint
    For more information about DNS namespaces that are supported by Exchange, see KB2269838.

    https://support.microsoft.com/en-us/help/2269838/microsoft-exchange-compatibility-with-single-label-domains-disjointed

    Ensure you meet these requirements in the last link and you will be fine.

    • Marked as answer by Andy DavidMVP Friday, December 20, 2019 12:26 PM
    Wednesday, December 18, 2019 8:32 PM
  • Andy:

    I appreciate the response, but it doesn't answer my question.  I'll explain:

    I do not know how Exchange 2016 determines if a TLD is valid.  It's possible that Exchange doesn't care and will accept any domain, even ones not listed by IANA, but I think that is unlikely.  It's also possible that Exchange has an internal, hard-coded list of valid TLDs that it refers to.  Or there may be some other mechanism(s) Exchange uses to validate the TLD.  For example, maybe it calls the IANA page on startup and loads valid TLDs into a table or something.  I just don't know.

    There are plenty of TLDs that weren't valid (structurally or otherwise) five years ago that are valid today.  Depending upon the mechanism that Exchange 2016 uses as described in the examples above, my concern remains valid.

    The first article you reference is applicable, but does not answer the question.  The second article you reference is very old and is applicable to Exchange 2010.  I wouldn't want to assume that it is applicable to Exchange 2016.

    Thanks again!

    Ken Morley


    Wednesday, December 18, 2019 9:18 PM
  • Andy:

    I appreciate the response, but it doesn't answer my question.  I'll explain:

    I do not know how Exchange 2016 determines if a TLD is valid.  It's possible that Exchange doesn't care and will accept any domain, even ones not listed by IANA, but I think that is unlikely.  It's also possible that Exchange has an internal, hard-coded list of valid TLDs that it refers to.  Or there may be some other mechanism(s) Exchange uses to validate the TLD.  For example, maybe it calls the IANA page on startup and loads valid TLDs into a table or something.  I just don't know.

    There are plenty of TLDs that weren't valid (structurally or otherwise) five years ago that are valid today.  Depending upon the mechanism that Exchange 2016 uses as described in the examples above, my concern remains valid.

    The first article you reference is applicable, but does not answer the question.  The second article you reference is very old and is applicable to Exchange 2010.  I wouldn't want to assume that it is applicable to Exchange 2016.

    Thanks again!

    Ken Morley


    Well, Exchange will pretty much let you enter anything. It you add <somedomain>.law as an accepted domain, I have no doubt it will be accepted. Exchange relies On Windows, it doesnt really maintain an internal domain list . The second article i referenced is not old however, it still is referenced by the 2019 articles, simply because the supported domain "types" have not changed. Microsoft would only update the article if the supportability had changed. 
    Wednesday, December 18, 2019 10:55 PM
  • Hi Ken,

    As Andy mentioned, for internal domain names, any TLD can be used. Because this is used for internal organization and cannot be found from the Internet. If you want to use the TLD with Internet, you should make sure the TLD is valid and available from the list of top-level domains maintained by the IANA. Exchange doesn't have an additional TLD list.

    Regards,

    Lydia Zhou


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Thursday, December 19, 2019 2:52 AM
  • Lydia:

    Thank you for your reply. 

    If I understand you correctly, Exchange 2016 does not validate the TLD and the choice of TLD is arbitrary.  Further, if a TLD is used that has not been accepted by IANA, that TLD cannot be used for external email because the TLD cannot be resolved using public DNS.  But that non-accepted TLD can still be used successfully with Exchange 2016 for internal purposes. 

    To be clear, I am only interested in using the .LAW TLD with external e-mail.  According to your response, Exchange 2016 simply doesn't validate ANY TLDs whether they are used internally or externally.  That design is surprising to me, but it provides the answer that I need.

    Thanks!

    Ken Morley

    Thursday, December 19, 2019 2:27 PM
  • Lydia:

    Thank you for your reply. 

    If I understand you correctly, Exchange 2016 does not validate the TLD and the choice of TLD is arbitrary.  Further, if a TLD is used that has not been accepted by IANA, that TLD cannot be used for external email because the TLD cannot be resolved using public DNS.  But that non-accepted TLD can still be used successfully with Exchange 2016 for internal purposes. 

    To be clear, I am only interested in using the .LAW TLD with external e-mail.  According to your response, Exchange 2016 simply doesn't validate ANY TLDs whether they are used internally or externally.  That design is surprising to me, but it provides the answer that I need.

    Thanks!

    Ken Morley

    Yea, didn't I say that?
    Thursday, December 19, 2019 3:35 PM
  • It's great that you get useful information from replies above. Here is a brief summary for quick reference.

    Question:

    My customer would like to add a new domain like CONTOSO.LAW to their existing Exchange 2016 system.

    Before attempting that, I thought it would be good to verify that Exchange 2016 supports that new TLD.  Can someone please either verify that ".LAW" is supported by Exchange 2016 and/or point me to the list of domains that Exchange 2016 does support?

    Summary:

    Exchange doesn't have an additional TLD list. For internal domain names, any TLD can be used. Because this is used for internal organization and cannot be found from the Internet.

    If you want to use the TLD with Internet, you should make sure the TLD is valid and available from the list of top-level domains maintained by the IANA. 

    Regards,

    Lydia Zhou


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Friday, December 20, 2019 1:12 AM