locked
Effect of using external DNS setting in Send Connector properties - E2K7 RRS feed

  • Question

  • In Send Connector properties, under the Network tab, it is possible to select this option:

    "Use the external DNS lookup settings on the Transport Server"

    Why would you use this option?

    What advantage would this have?

    What DNS servers would be used ?

    Normally, it is those configured on the NIC, right? 

    Is it correct that this would have no effect on local name resolution between the transport server and internal DNS servers?


    Friday, May 13, 2011 2:14 PM

Answers

  • If you have a closed network and don’t allow your dedicated DNS servers to go out to the web you need something to resolve addresses when you need to send email. So the best thing to do is to tell the connector about external DNS servers. Your internal network stays largely isolated from resolving anything external and the email servers can still resolve. All shiny and good.
     
    You would use servers that your ISP told you about.
     
     
    "Le Pivert" wrote in message news:a093f75f-c227-4c86-b779-7a732b378a5d...

    In Send Connector properties, under the Network tab, it is possible to select this option:

    "Use the external DNS lookup settings on the Transport Server"

    Why would you use this option?

    What advantage would this have?

    What DNS servers would be used ?

    Normally, it is those configured on the NIC, right?

    Is it correct that this would have no effect on local name resolution between the transport server and internal DNS servers?



    Mark Arnold, Exchange MVP.
    Friday, May 13, 2011 4:15 PM
  • On Fri, 13 May 2011 14:14:43 +0000, Le Pivert wrote:
     
    >
    >
    >In Send Connector properties, under the Network tab, it is possible to select this option:
    >
    >"Use the external DNS lookup settings on the Transport Server"
    >
    >Why would you use this option?
     
    If your internal DNS servers are capable of resolving addresses for
    names outside of your own DNS zones then you usually don't need this.
    If your internal DNS servers are restricted from resolving any names
    from DNS zones not on your DNS servers then you'll have to use some
    other DNS server(s) to resolve names (or use a smart host).
     
    >What advantage would this have?
     
    Usually, none.
     
    >What DNS servers would be used ?
     
    That depends on how you've configured the transport server settings.
     
    >Normally, it is those configured on the NIC, right?
     
    If you have only one NIC then there's no sense in configuring the
    transport server to use the DNS configure on the external NIC.
     
    If you have an external NIC then the transport server might be
    configured to use it (and the DNS configured on that NIC).
     
    If you have only one NIC then you'd configure the transport server to
    use one, or more, external DNS and *not* the "external NIC".
     
    >Is it correct that this would have no effect on local name resolution between the transport server and internal DNS servers?
     
    That's correct.
     
    ---
    Rich Matheisen
    MCSE+I, Exchange MVP
     

    --- Rich Matheisen MCSE+I, Exchange MVP
    Saturday, May 14, 2011 2:20 AM
  • Hi,

    you can also refer to this link:

    http://technet.microsoft.com/en-us/library/bb123514.aspx

    Use the External DNS Lookups tab to specify whether to use the DNS servers that are configured on a network adapter installed on this server or to use specific DNS servers when resolving the addresses of mail servers for external mail delivery. External DNS servers are used by Send connectors that are configured to use the external DNS lookup configuration on the transport server. When messages are routed to these Send connectors, the external DNS lookup settings that are configured for the source servers are used to resolve IP addresses for the delivery destination

    >I've created a separate Send Connector for the specific domain in question, just to be sure there will be no effect on the "primary" Send Connector (the one used by default: SMTP * ).

    sure, the "primary" send connector will still use DNS server in your domain.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.
    Tuesday, May 17, 2011 2:23 AM

All replies

  • If you have a closed network and don’t allow your dedicated DNS servers to go out to the web you need something to resolve addresses when you need to send email. So the best thing to do is to tell the connector about external DNS servers. Your internal network stays largely isolated from resolving anything external and the email servers can still resolve. All shiny and good.
     
    You would use servers that your ISP told you about.
     
     
    "Le Pivert" wrote in message news:a093f75f-c227-4c86-b779-7a732b378a5d...

    In Send Connector properties, under the Network tab, it is possible to select this option:

    "Use the external DNS lookup settings on the Transport Server"

    Why would you use this option?

    What advantage would this have?

    What DNS servers would be used ?

    Normally, it is those configured on the NIC, right?

    Is it correct that this would have no effect on local name resolution between the transport server and internal DNS servers?



    Mark Arnold, Exchange MVP.
    Friday, May 13, 2011 4:15 PM
  • On Fri, 13 May 2011 14:14:43 +0000, Le Pivert wrote:
     
    >
    >
    >In Send Connector properties, under the Network tab, it is possible to select this option:
    >
    >"Use the external DNS lookup settings on the Transport Server"
    >
    >Why would you use this option?
     
    If your internal DNS servers are capable of resolving addresses for
    names outside of your own DNS zones then you usually don't need this.
    If your internal DNS servers are restricted from resolving any names
    from DNS zones not on your DNS servers then you'll have to use some
    other DNS server(s) to resolve names (or use a smart host).
     
    >What advantage would this have?
     
    Usually, none.
     
    >What DNS servers would be used ?
     
    That depends on how you've configured the transport server settings.
     
    >Normally, it is those configured on the NIC, right?
     
    If you have only one NIC then there's no sense in configuring the
    transport server to use the DNS configure on the external NIC.
     
    If you have an external NIC then the transport server might be
    configured to use it (and the DNS configured on that NIC).
     
    If you have only one NIC then you'd configure the transport server to
    use one, or more, external DNS and *not* the "external NIC".
     
    >Is it correct that this would have no effect on local name resolution between the transport server and internal DNS servers?
     
    That's correct.
     
    ---
    Rich Matheisen
    MCSE+I, Exchange MVP
     

    --- Rich Matheisen MCSE+I, Exchange MVP
    Saturday, May 14, 2011 2:20 AM
  • And the External DNS servers to be used are those that I would designate in Server Configuration for the server in question (I only have one Exchange server), in Properties, under the DNS External Lookups, correct?

    That SEEMS pitifully obvious, but I'll ask anyway.

    I've created a separate Send Connector for the specific domain in question, just to be sure there will be no effect on the "primary" Send Connector (the one used by default: SMTP * ).

    Monday, May 16, 2011 8:15 PM
  • Reading this article right now - looks like that's how to do it:

    http://technet.microsoft.com/en-us/library/aa997166(EXCHG.80).aspx

     

    Monday, May 16, 2011 8:49 PM
  • Hi,

    you can also refer to this link:

    http://technet.microsoft.com/en-us/library/bb123514.aspx

    Use the External DNS Lookups tab to specify whether to use the DNS servers that are configured on a network adapter installed on this server or to use specific DNS servers when resolving the addresses of mail servers for external mail delivery. External DNS servers are used by Send connectors that are configured to use the external DNS lookup configuration on the transport server. When messages are routed to these Send connectors, the external DNS lookup settings that are configured for the source servers are used to resolve IP addresses for the delivery destination

    >I've created a separate Send Connector for the specific domain in question, just to be sure there will be no effect on the "primary" Send Connector (the one used by default: SMTP * ).

    sure, the "primary" send connector will still use DNS server in your domain.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.
    Tuesday, May 17, 2011 2:23 AM
  • On Mon, 16 May 2011 20:15:38 +0000, Le Pivert wrote:
     
    >And the External DNS servers to be used are those that I would designate in Server Configuration for the server in question (I only have one Exchange server), in Properties, under the DNS External Lookups, correct?
     
    That's correct. Or you can use the set-transportserver cmdlet to do
    that.
     
    >That SEEMS pitifully obvious, but I'll ask anyway.
    >
    >I've created a separate Send Connector for the specific domain in question, just to be sure there will be no effect on the "primary" Send Connector (the one used by default: SMTP * ).
     
    Not unless you configure it to use external DNS.
     
    ---
    Rich Matheisen
    MCSE+I, Exchange MVP
     

    --- Rich Matheisen MCSE+I, Exchange MVP
    Tuesday, May 17, 2011 2:53 AM
  • Please let me know if we can remove "ExternalDNSServers" IP address from send connector. So that I can add some new IP address.

    Thanks,

    Vinod

    Thursday, April 17, 2014 10:33 AM