sending DHCPINFORM message from non-DHCP client

Question

Suppose I have static ip in a subnet that has DHCP server. If i gonna send DHCPINFORM message to the server, what will happen ?

amit

Answer 1

As per RFC-2131 tropic 4.3.5 for DHCPINFORM message:

"The DHCP server responds to a DHCPINFORM message by sending a DHCPACK message directly to the address given in the 'ciaddr' field of the DHCPINFORM message. The server MUST NOT send a lease expiration time to the client and SHOULD NOT fill in 'yiaddr'. The server includes other parameters in the DHCPACK message as defined in section 4.3.1. "

1. Since a "DHCPAck" message does not mandate to add all requested network configuration parameters, a DHCP server is free to respond to a "DHCPInform" message, with/without requested parameter responses (implementation dependent), provided the client's static ip settings are validated under dhcp server pools.

2. Also, the dhcp-client may receive "DHCPAck" messages from many DHCP servers in response to its "DHCPInform" message. The client need to filters all of the "DHCPAck" messages received from DHCP servers to extract response parameters.

[ Example: The dhcp-client may searches each received "DHCPAck" message for a predetermined vendor-specific tag. If a "DHCPAck" message includes a predetermined vendor-specific tag, the dhcp-client extracts response parameters from this message. ]