Cisco CCNA mock exam questions sample test – Question 153

Group the special DHCP messages exchanged over the network, on the left, into the different transmission types, on the right.

Select and Place:


Correct Answer:


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

The following steps are used to allocate IP address dynamically using a Cisco IOS DHCP server:
1. The client device broadcasts a DHCPDISCOVER broadcast message to locate a Cisco IOS DHCP server.
2. The Cisco IOS DHCP server replies with a DHCPOFFER unicast message containing configuration parameters such as an IP address, a MAC address, a domain name, and a lease for the IP address for the client device.
3. The client sends back a DHCPREQUEST broadcast, which is a formal request for the offered IP address to the Cisco IOS DHCP server.
4. The Cisco IOS DHCP server replies to client device with DHCPACK unicast message acknowledging the allocation of the IP address to this client device.
While DHCP is very useful in reducing the administrative burden of issuing IP configurations in a large network, Cisco best practices call for using static IP addressing in a small (6 or fewer hosts) network.

Infrastructure Services
Configure and verify DHCP on a router (excluding static reservations)
Cisco Documentation > Cisco IOS IP Configuration Guide, Release 12.2 > Part 1: IP Addressing and Services > Configuring DHCP