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Subnets and DHCP Scopes RRS feed

  • Question

  • I have a question about subnetting and DHCP Scopes.  If you have say four subnets on your network can you setup four DHCP scopes and have your DHCP server manage the IP address assignments for all of them or do you have to set up a DHCP Relay Agent for each subnet?  Thanks for your help.

    Michael T. Glenn


    Michael T. Glenn

    Thursday, February 19, 2015 12:36 AM

Answers

  • It depends on your network structure. If you need more subnets of different physical networks, then Relay Agent is needed.

    This may help to understand RA

    https://technet.microsoft.com/en-us/library/cc779610(v=ws.10).aspx

    Regards

    Milos

    • Proposed as answer by Susie Long Monday, February 23, 2015 3:16 AM
    • Marked as answer by Susie Long Monday, March 9, 2015 5:14 AM
    Thursday, February 19, 2015 7:10 AM
  • You will need to configure dhcp relay agent / IP helper address on router interfaces connected to the clients' subnets. Without IP helpers / relay agents, DHCP server will receive DHCP requests from local subnet only (the subnet directly connected to DHCP server). If the subnets are isolated  (no routing of traffic between clients' subnets and the network that hosts DHCP server), then you can add additional NICs to your DHCP server and connect these to clients' subnets, so that DHCP server will be able to receive broadcasts from all clients.

    Gleb.

    • Proposed as answer by Susie Long Monday, February 23, 2015 3:16 AM
    • Marked as answer by Susie Long Monday, March 9, 2015 5:14 AM
    Thursday, February 19, 2015 9:50 AM

All replies

  • It depends on your network structure. If you need more subnets of different physical networks, then Relay Agent is needed.

    This may help to understand RA

    https://technet.microsoft.com/en-us/library/cc779610(v=ws.10).aspx

    Regards

    Milos

    • Proposed as answer by Susie Long Monday, February 23, 2015 3:16 AM
    • Marked as answer by Susie Long Monday, March 9, 2015 5:14 AM
    Thursday, February 19, 2015 7:10 AM
  • You will need to configure dhcp relay agent / IP helper address on router interfaces connected to the clients' subnets. Without IP helpers / relay agents, DHCP server will receive DHCP requests from local subnet only (the subnet directly connected to DHCP server). If the subnets are isolated  (no routing of traffic between clients' subnets and the network that hosts DHCP server), then you can add additional NICs to your DHCP server and connect these to clients' subnets, so that DHCP server will be able to receive broadcasts from all clients.

    Gleb.

    • Proposed as answer by Susie Long Monday, February 23, 2015 3:16 AM
    • Marked as answer by Susie Long Monday, March 9, 2015 5:14 AM
    Thursday, February 19, 2015 9:50 AM
  • If my subnets are all subnets off of the same network such as 192.168.43.0/19 and the subnets are 192.168.43.0

    192.168.43.32 and so on can a single router handle all the subnets as relay agents?  I'm assuming I don't need separate routers for each subnet or separate NIC's for each subnet.


    Michael T. Glenn

    Thursday, February 19, 2015 5:41 PM