11.3.3 Dynamic Addressing with DHCP Quiz Answers. Networking Basics Module 11 quiz exam answers
1. Match each description with an appropriate IP address.
Networking Basics Module 11 quiz
Explanation: Place the options in the following order:
|a client initiating a message to find a DHCP server
|a DHCP server responding to the initial request by a client
|the client accepting the IP address provided by the DHCP server
|the DHCP server confirming that the address lease has been accepted
2. Which two reasons generally make DHCP the preferred method of assigning IP addresses to hosts on large networks? (Choose two.)
- It eliminates most address configuration errors.
- It ensures that addresses are only applied to devices that require a permanent address.
- It guarantees that every device that needs an address will get one.
- It provides an address only to devices that are authorized to be connected to the network.
- It reduces the burden on network support staff.
Explanation: DHCP is generally the preferred method of assigning IP addresses to hosts on large networks because it reduces the burden on network support staff and virtually eliminates entry errors. However, DHCP itself does not discriminate between authorized and unauthorized devices and will assign configuration parameters to all requesting devices. DHCP servers are usually configured to assign addresses from a subnet range, so there is no guarantee that every device that needs an address will get one.
3. Which message does an IPv4 host use to reply when it receives a DHCPOFFER message from a DHCP server?
Explanation: When the client receives the DHCPOFFER from the server, it sends back a DHCPREQUEST broadcast message. On receiving the DHCPREQUEST message, the server replies with a unicast DHCPACK message.
4. Which destination IPv4 address does a DHCPv4 client use to send the initial DHCP Discover packet when the client is looking for a DHCP server?
- the IP address of the default gateway
Explanation: Broadcast communications on a network may be directed or limited. A directed broadcast is sent to all hosts on a specific network. A limited broadcast is sent to 255.255.255.255. When a DHCP client needs to send a DHCP Discover packet in order to seek DHCP servers, the client will use this IP address of 255.255.255.255 as the destination in the IP header because it has no knowledge of the IP addresses of DHCP servers.
5. Which type of packet is sent by a DHCP server after receiving a DHCP Discover message?
- DHCP ACK
- DHCP Discover
- DHCP Offer
- DHCP Request
Explanation: When a DHCP server receives a DHCP Discover packet from a client, the server responds with a DHCP Offer packet to let the client know that an IP address is available and reserved for the client.
6. What is one advantage of using DHCP to assign addresses to mobile devices?
- Address leases are temporary and are returned to the pool when the device is turned off.
- Addresses are permanently assigned to the mobile device and are valid on any network.
- Using DHCP creates many more registered IPv4 addresses.
- DHCP enables multiple internal IPv4 addresses to use a single registered global address.
Explanation: A benefit of DHCP is that an address is not permanently assigned to a host but is only leased for a period of time. If the host is powered down or taken off the network, the address is returned to the pool for reuse. This is especially helpful with mobile users that come and go on a network.
7. Refer to the exhibit. A home wireless router is configured to act as a DHCP server. The IP address range is configured to be 192.168.0.100 – 149. What IP address will be assigned automatically to the first device that connects to the wireless router?
Explanation: When the first device connects to the wireless router, it will receive the first address that is configured in the pool. Subsequent devices will receive an address from the pool until all addresses are assigned.
8. Refer to the exhibit. PC1 is configured to obtain a dynamic IP address from the DHCP server. PC1 has been shut down for two weeks. When PC1 boots and tries to request an available IP address, which destination IP address will PC1 place in the IP header?
Explanation: When a host boots and has been configured for dynamic IP addressing, the device tries to obtain a valid IP address. It sends a DHCPDISCOVER message. This is a broadcast message because the DHCP server address is unknown (by design). The destination IP address in the IP header is 255.255.255.255 and the destination MAC address is FF:FF:FF:FF:FF:FF.
9. Which type of server dynamically assigns an IP address to a host?
Explanation: DHCP servers can be computers or networking devices that are configured to assign IPv4 addresses to network connected devices.
10. Which three statements describe a DHCP Discover message? (Choose three.)
- The source MAC address is 48 ones (FF-FF-FF-FF-FF-FF).
- The destination IP address is 255.255.255.255.
- The message comes from a server offering an IP address.
- The message comes from a client seeking an IP address.
- All hosts receive the message, but only a DHCP server replies.
- Only the DHCP server receives the message.
Explanation: When a host configured to use DHCP powers up on a network it sends a DHCPDISCOVER message. FF-FF-FF-FF-FF-FF is the L2 broadcast address. A DHCP server replies with a unicast DHCPOFFER message back to the host.
11. A host PC is attempting to lease an address through DHCP. What message is sent by the server to let the client know it is able to use the provided IP information?
Explanation: When a host uses DHCP to automatically configure an IP address, the typically sends two messages: the DHCPDISCOVER message and the DHCPREQUEST message. These two messages are usually sent as broadcasts to ensure that all DHCP servers receive them. The servers respond to these messages using DHCPOFFER, DHCPACK, and DHCPNACK messages, depending on the circumstance.