CISCO CCNA 200-301 Q143

Which type of Dynamic Host Configuration Protocol (DHCP) transmission is used by a host to forward a DHCPDISCOVER packet to locate a DHCP server on the network?

A. unicast
B. broadcast
C. multicast
D. anycast

Correct Answer: B

Hosts broadcast DHCPDISCOVER messages to locate a DHCP server. The following steps are followed during the allocation of the IP address dynamically using a DHCP server:

– The client device broadcasts a DHCPDISCOVER message to locate a DHCP server.
– The DHCP server replies with a DHCPOFFER unicast message with configuration parameters, such as an IP address, a MAC address, a domain name, and a lease for the IP address for the client device.
– The client returns a DHCPREQUEST broadcast, which is a formal request for the offered IP address to the DHCP server.
– The DHCP server replies to client device with DHCPACK unicast message, acknowledging the allocation of the IP address to this client device.

Dynamic Host Configuration Protocol (DHCP) is an enhancement over Bootstrap Protocol (BOOTP) and is used to automate the distribution of IP address to clients from a central server. BOOTP protocol was also used to distribute IP addresses, but was inflexible to changes in the network.

DHCP offers the following three advantages that also addressed the inflexibility of the BOOTP protocol:
– Automatic allocation of permanent IP addresses
– Automatic allocation of time bound (leased) IP addresses
– Provision of assigning static IP address or defining a pool of reserved IP address DHCP does not use multicast messages.

Anycast is a concept of IPv6 protocol and is not valid type used by DHCP.