Distributing DNS load via DHCP

Jeff Wieland wieland at purdue.edu
Fri Dec 16 14:55:54 UTC 2011

We have a fairly large pool of address, and we'd like to distribute
the DNS load on this pool between two DNS servers.

Roughly, what I was thinking of doing is:

group {
    default-lease-time 21600;
    max-lease-time 28800;
    option domain-name "myuni.edu";
    option domain-name-servers,;

    subnet netmask {
        option routers;
        # Select the DNS server order by examining the last bit of
        # the hardware address
        if (suffix(binary-to-ascii(2, 8, ":", hardware), 1) = "1") {
            option domain-name-servers,;
        } else {
            option domain-name-servers,;

        pool {
            deny dynamic bootp clients;

Or would I be better off doing something with classes/subclasses?
I'm concerned about the performance impact of the if statement.

          Jeff Wieland            |         Purdue University
   Network Systems Administrator  |        ITN&S Data Networks
       Voice: (765)496-8234       |        155 S. Grant Street
        FAX: (765)494-6620        |   West Lafayette, IN 47907-2115

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