Does DHCP client receive DHCP NAK if any of the parameters are wrong in DHCP Release?

I am building a dhcp client using C on Ubuntu 9.04. Now I send a dhcp release to the dhcp server, it sends no ack as expected. I was wondering if it sends any DHCP NAK if any of the parameters are wrong开发者_开发百科.

There is one more problem. After sending DHCP Release my internet is still working. Also when I do ifconfig it still shows the ip address of eth0. But when I do dhclient -r internet does not work and ifconfig does not show the ip address of eth0.

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Are you using tcpdump to inspect the packet traffic while you debug the handshake? That should show you if your server's implementation sends a NAK. RFC 2131: Dynamic Host Configuration Protocol indicates that there is a DHCPNAK.

DHCPNAK -- Server to client indicating client's notion of network address is incorrect (e.g., client has moved to new subnet) or client's lease as expired.