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DHCP Failover

    Question

  • Hi,

    We currently have two DHCP servers configured on Windows 2008 R2, today we discovered that one of the DHCP server's had maxed its IP distribution and could no longer give out any new IP's so some PC's did not get an IP,  however the other DHCP server had another 50 Ip's available, why did the PC not go to the other DHCP to get an IP (or why did the DHCP server not tell the pc try the other DHCP server)?

    Or is their something I need to configure to say, if you cant get an IP from this DHCP server try another?

    Thanks 

    Friday, November 18, 2011 10:03 AM

Answers

  • It might be related with your network configuration. If you use switches and VLANs in your environemnt, you need to define IPHelper(s) list/DHCP Relay Agent to redirect DHCP broadcast traffic to DHCP servers. So, make sure if your second DHCP server is listed in IPHelper configuration on switch(es)/DHCP Relay Agent configuration

    One more thin, check if that second DHCP is authorized and its scopes are activated. And finally, check if split scope pool is not excluded completely.

    After those steps, everything shoudl work fine. If you wish, you may also visit my blog and check an article for DHCp split-scope wizard for 2008R2 server at
    http://kpytko.wordpress.com/2011/10/07/dhcp-split-scope-wizard/


    Regards, Krzysztof ---- Visit my blog at http://kpytko.wordpress.com
    • Marked as answer by Tiger Li Thursday, November 24, 2011 5:53 AM
    Friday, November 18, 2011 10:34 AM
  • In addition to iSiek's response which is correct, here is some additional information on the DHCP relay process:

    The DHCP Relay Agent
    http://itgeared.com/dhcp-relay-agent


    Guides and tutorials, visit ITGeared.com.

    itgeared.com facebook twitter youtube
    • Marked as answer by Tiger Li Thursday, November 24, 2011 5:53 AM
    Friday, November 18, 2011 2:47 PM
  • Hi ziwez0,

     

    Thanks for posting here.

     

    In addition, we may also check if the scope on secondary DHCP server has been activated and server had also been authorized and we also need to ensure that both servers are in same subnet otherwise DHCP relay should be involved like what discussed in other replies.

     

    Meanwhile, have you got any error or warring that regarding with DHCP service form event viewer on the secondary DHCP server ? have also deployed these two DHCP servers in DHCP Split Scope designing ?

     

    Thanks for clarify.

     

    Tiger Li


    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.
    • Marked as answer by Tiger Li Thursday, November 24, 2011 5:53 AM
    Tuesday, November 22, 2011 2:45 AM

All replies

  • It might be related with your network configuration. If you use switches and VLANs in your environemnt, you need to define IPHelper(s) list/DHCP Relay Agent to redirect DHCP broadcast traffic to DHCP servers. So, make sure if your second DHCP server is listed in IPHelper configuration on switch(es)/DHCP Relay Agent configuration

    One more thin, check if that second DHCP is authorized and its scopes are activated. And finally, check if split scope pool is not excluded completely.

    After those steps, everything shoudl work fine. If you wish, you may also visit my blog and check an article for DHCp split-scope wizard for 2008R2 server at
    http://kpytko.wordpress.com/2011/10/07/dhcp-split-scope-wizard/


    Regards, Krzysztof ---- Visit my blog at http://kpytko.wordpress.com
    • Marked as answer by Tiger Li Thursday, November 24, 2011 5:53 AM
    Friday, November 18, 2011 10:34 AM
  • In addition to iSiek's response which is correct, here is some additional information on the DHCP relay process:

    The DHCP Relay Agent
    http://itgeared.com/dhcp-relay-agent


    Guides and tutorials, visit ITGeared.com.

    itgeared.com facebook twitter youtube
    • Marked as answer by Tiger Li Thursday, November 24, 2011 5:53 AM
    Friday, November 18, 2011 2:47 PM
  • Hi ziwez0,

     

    Thanks for posting here.

     

    In addition, we may also check if the scope on secondary DHCP server has been activated and server had also been authorized and we also need to ensure that both servers are in same subnet otherwise DHCP relay should be involved like what discussed in other replies.

     

    Meanwhile, have you got any error or warring that regarding with DHCP service form event viewer on the secondary DHCP server ? have also deployed these two DHCP servers in DHCP Split Scope designing ?

     

    Thanks for clarify.

     

    Tiger Li


    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.
    • Marked as answer by Tiger Li Thursday, November 24, 2011 5:53 AM
    Tuesday, November 22, 2011 2:45 AM