Chapter 5 - DHCP Flashcards
What are the 4 message types in a client / server DHCP exchange?
DHCPDISCOVER (brodcast) client to any available server
DHCPOFFER (unicast) server to client
DHCPREQUEST (broadcast) client to server
DHCPACK (unicast) server to client providing IP information
What is the DHCP debug message DHCPDECLINE indicate?
DHCPDECLINE - This message that is sent from the client to the server indicates that the address is already in use.
What is the DHCP debug message DHCPNAK indicate?
DHCPNAK - The server sends a refusal to the client for its request for configuration.
What does the DHCP debug message DHCPRELEASE indicate?
DHCPRELEASE - The client tells a server that it is giving up a lease.
What does the DHCP debug message DHCPINFORM indicate?
DHCPINFORM - A client already has an IP address but is requesting other configuration parameters that the DHCP server is configured to deliver, such as a DNS address.
How can DHCP requests get to a DHCP server on a different subnet?
Configured the ip helper-address. The multilayer switch must have a Layer 3 IP address that will receive the client brodcast (all F’s) DHCP request. This address may be a router port or an SVI. The redirected request is sent as unicast traffic to the remote DHCP server.
Switch(config)# interface vlan 55
Switch(config-if)# ip helper-address 192.168.1.244
In this example the DHCP server is at 192.168.1.244
What is DHCP Option 43 used for?
Vendor-encapsulated options, which enable vendors to have their own list of options on the server. For example, you can use it to tell a lightweight AP where the WLC is.
What is DHCP Option 69 used for?
Option 69: SMTP server, if you want to specify available SMTP servers to the client.
What is DHCP Option 70 used for?
Option 70: POP3 server, if you want to specify available POP3 servers to the client.
What is DHCP Option 150 used for?
Option 150: TFTP server, which enables your phones to access a list of TFTP servers.
