2

Assume that I have a router with DHCP server on it (well, it is actually a dd-wrt router). After rebooting the router, all the DHCP clients's hostnames are lost: I couldn't see the names of the clients except IP addresses in the "active clients" page of the "LAN" status tab in dd-wrt.

The DHCP clients wouldn't resend their hostnames automatically unless they are trying to renew their IPs. Is there any way that I can force the clients to resend?

Thanks a lot!

2 Answers2

3

The DHCP Client FQDN option (option 81) allows the client to send it's FQDN to the DHCP server, and the DHCP server can be configured to register this with DNS.

This gives a mapping between IP address and Hostname independent of the DHCP server - so you could then use reverse DNS to get the hostnames from the IP addresses.

dunxd
  • 9,632
  • 22
  • 81
  • 118
2

Hosts cannot be forced to renew their lease, unless you trigger them. This means you would need to do an 'ipconfig /renew' or 'dhclient eth0' or similar from each system to force it to renew the lease.

However, with DD-WRT you can have DHCP return the same IP address for each host in your network, and start the DNS service on your router and have it map address to name. Depending on the number of computers in your network, this could take some time to setup:

DNS on DD-WRT

Hope that helps.

Vince Berk
  • 159
  • 2