man dhcp-options

      option fqdn.no-client-update flag;

          When the client sends this, if it is true, it means the client \\
          will not attempt  to update its A record.
          When sent by the server to the client, it means that the client \\
          should not update its own A record.

       option fqdn.server-update flag;

          When  the  client  sends  this to the server, it is requesting that the server update its A record.   When sent by the
          server, it means that the server has updated (or is about to update) the client's A record.


#
#   DHCP Server Config File
#
  ddns-update-style none;
  ignore client-updates;

  lease-file-name "/var/lib/dhcpd/dhcpd.leases";
  authoritative;

  default-lease-time                      86400;   # 24 hours
  max-lease-time                          172800;  # 48 hours

  subnet 192.168.1.0 netmask 255.255.255.0 {
        range         192.168.1.101   192.168.1.200;
        ddns-domainname                       "home.lan";
        option domain-name                    "home.lan";
        option domain-name-servers            192.168.1.5;
        option netbios-name-servers           192.168.1.5;
        option netbios-dd-server              192.168.1.5;
        option routers                        192.168.1.5;
        option ntp-servers                    192.168.1.5;
        ddns-update-style                     ad-hoc;
        option netbios-node-type              8;
        option ip-forwarding                  off;
        option non-local-source-routing       off;
        option perform-mask-discovery         off;
        option router-discovery               off;
        option tcp-keepalive-garbage          off;
  }
  
  
  
http://technet.microsoft.com/en-us/library/cc977343.aspx