pxe-boot dhcp configuration

[stu2000]

Hey all, can you guys look over my configuration and check Im not doing antyhing silly. There is already a dhcp router set up at 192.168.1.1 but I want to set this one up to override for specified mac addresses for pxe booting. The service stops and starts correctly, but it appears that no computers are picking this up. My brother seems to figure that you just cant have two dhcp servers on the same network, but then what would the authoritative line be for, and I got the impression that you could from reading about it in the man for dhcpd.conf

# Stuarts pxe-boot dhcp server

authoritative;

ddns-update-style interim;

allow booting;
allow bootp;

ignore client-updates;

subnet 192.168.1.0 netmask 255.255.255.0 {

    # Put all pxe-booting clients here
    host pxe-client {
        # Host specific parameters
        hardware ethernet 00:21:9B:16:1B:F6;
    }

    host another-pxe-client {
        hardware ethernet 00:21:9B:16:26:FA;
    }

    option routers              192.168.1.1;                 # Local Router ip
    option domain-name-servers  8.8.8.8;                     # GOOGLE DNS
    option subnet-mask          255.255.255.0;
    range                       192.168.1.200 192.168.1.254;
    filename                    "/pxelinux.0";
    default-lease-time          21600;
    max-lease-time              43200;
    next-server                 192.168.1.2;                 # this servers ip
    deny                        unknown-clients;             # only apply to specified clients
}

[atreyu]

i've run into this problem before (2 DHCP servers on the same LAN), and the authoritative declarative did not work for me like I had hoped. btw, you can have two DHCP servers on the same subnet, it is just a matter of configuring them properly. also, if there is no way for the client to specify its preferred DHCP server, then it is hit or miss, who responds to the client query first.

can you control/configure the DHCP server at 192.168.1.1? can you force it to only respond to certain MAC addresses as well? can you disable it temporarily, too, to make sure that the DHCP sever on 192.168.1.2 is working otherwise?

[stu2000]

unfortunately not, but this was just for testing and at least in the real-life situation I wont have to worry about having 2 dhcps. It would work only when I put this dhcp server in its own lan not connected to the other dhcp server, The other problem with having two dhcp servers within the same subnet is making sure that the ips cannot overlap, and there is no sure-fire way it seems to ensure that a client will use one server instead of the other. I had hoped that this wouldnt really act as a dhcp server so much as just a pxe-boot server for manually configured clients. Evidently that seems impossible.

[atreyu]

i take it you cannot specify the preferred DHCP/PXE-boot server on the client (like in the BIOS, or whatever)?

[stu2000]

No we need this to be pretty much automated from the dhcp point of view. Being a dhcp config i can write a script to easily change it and restart the process. Quite difficult to write a script to alter machines' bios