DHCP client request for specific hostname per interface.

Chris Buxton chris.p.buxton at gmail.com
Sat Dec 11 07:37:25 UTC 2010

On Dec 10, 2010, at 11:02 AM, Vyto Grigaliunas wrote:
> Hi...
> Thanks for the reply.
> We have migrated our DHCP service over to InfoBlox appliances, but it
> appears that the InfoBlox DHCP servers will only accept the first instance
> of a requested DHCP client hostname for DDNS update and ignore duplicate
> requests for the same name.

Yes, this is standard behavior for ISC DHCP. The two interfaces look to dhcpd to be different clients, because they have different MAC addresses.

A solution I've deployed on a customer's network was to add "-wifi" to the ddns-hostname of every lease in all wireless networks. Within each wireless network's declaration in dhcpd.conf, we added:

ddns-hostname = concat(option host-name ,"-wifi");

Obviously, this isn't a perfect solution. For example, clients with very long hostnames could theoretically be assigned a hostname too long to fit in a DNS label (63 characters). Anyone with "-wifi" already set in their hostname would have a weird result. But in practice neither was occurring at this particular client.

Chris Buxton
BlueCat Networks

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