Hacker News Reader

How can a lease be "unused" if it hasn't expired and the client that requested it never released it? Are you saying that the DHCP server pings (ICMP or ARP) each address and re-leases the ones that don't get a response?

View on HN

Well actually the result of "running out" of addresses is undefined and up to the individual hardware manufacturer, so theoretically they could do whatever they want. A high-traffic WAP might want to simply boot the oldest lease if they can't assign more than a certain number of addresses.

Keep in mind if aa client wants an IP, it is supposed to do DHCP discovery every time it connects to the network, even if it's lease isn't up. See http://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Prot...

Are you saying that the DHCP server pings (ICMP or ARP) each address and re-leases the ones that don't get a response?

The DHCP will ping an address before leasing it, and if it gets a response then it will not lease that address.

I don't think this is true at our office (running a Cisco DHCP server). We get conflicts when putting a device with a static IP in the dhcp range, and I'm almost sure that they respond to ping.

Reply on news.ycombinator.com