Module 7 Pre-Assessment

Front

When PC1 boots and tries to request an available IP address from the DHCP server, which destination IP address will PC1 place in the IP header?

Back

255.255.255.255

Front

A company uses DHCP servers to dynamically assign IPv4 addresses to employee workstations. The address lease duration is set as 5 days. An employee returns to the office after an absence of one week. When the employee boots the workstation, it sends a message to obtain an IP address. Which Layer 2 and Layer 3 destination addresses will the message contain?

Back

FF-FF-FF-FF-FF-FF and 255.255.255.255

Answer explanation

When the lease of a dynamically assigned IPv4 address has expired, a workstation will send a DHCPDISCOVER message to start the process of obtaining a valid IP address. Because the workstation does not know the addresses of DHCP servers, it sends the message via broadcast, with destination addresses of FF-FF-FF-FF-FF-FF and 255.255.255.255.

Front

Which command will allow a network administrator to check the IP address that is assigned to a particular MAC address?

Back

Router# show ip dhcp binding

Answer explanation

The show ip dhcp binding command will show the leases, including IP addresses, MAC addresses, lease expiration, type of lease, client ID, and user name.

Front

Which message does an IPv4 host use to reply when it receives a DHCPOFFER message from a DHCP server?

Back

DHCPREQUEST

Answer 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.

Front

Which command enables the interface to acquire an IPv4 address automatically from an ISP in the interface configuration mode of a router?

Back

ip address dhcp

Answer explanation

The ip address dhcp interface configuration command configures an Ethernet interface as a DHCP client. The service dhcp global configuration command enables the DHCPv4 server process on the router. The ip helper-address command is issued to enable DHCP relay on the router. The ip dhcp pool command creates the name of a pool of addresses that the server can assign to hosts.

Front

Which set of commands will configure a router as a DHCP server that will assign IPv4 addresses to the 192.168.100.0/23 LAN while reserving the first 10 and the last addresses for static assignment? Options: ip dhcp excluded-address 192.168.100.1 192.168.100.10ip dhcp excluded-address 192.168.100.254ip dhcp pool LAN-POOL-100network 192.168.100.0 255.255.255.0ip default-gateway 192.168.100.1, ip dhcp excluded-address 192.168.100.1 192.168.100.10ip dhcp excluded-address 192.168.101.254ip dhcp pool LAN-POOL-100network 192.168.100.0 255.255.254.0default-router 192.168.100.1, dhcp pool LAN-POOL-100ip dhcp excluded-address 192.168.100.1 192.168.100.9ip dhcp excluded-address 192.168.100.254network 192.168.100.0 255.255.254.0default-router 192.168.101.1, ip dhcp excluded-address 192.168.100.1 192.168.100.9ip dhcp excluded-address 192.168.101.254ip dhcp pool LAN-POOL-100ip network 192.168.100.0 255.255.254.0ip default-gateway 192.168.100.1

Back

ip dhcp excluded-address 192.168.100.1 192.168.100.10ip dhcp excluded-address 192.168.101.254ip dhcp pool LAN-POOL-100network 192.168.100.0 255.255.254.0default-router 192.168.100.1

Answer explanation

The /23 prefix is equivalent to a network mask of 255.255.254.0. The network usable IPv4 address range is 192.168.100.1 to 192.168.101.254 inclusive. The commands dhcp pool , ip default-gateway , and ip network are not valid DHCP configuration commands.

Front

Which kind of message is sent by a DHCP client when its IP address lease has expired?

Back

a DHCPREQUEST unicast message​

Answer explanation

When the IP address lease time of the DHCP client expires, it sends a DHCPREQUEST unicast message directly to the DHCPv4 server that originally offered the IPv4 address.

Front

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?

Back

DHCPACK

Answer 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.

Front

What is a result when the DHCP servers are not operational in a network?

Back

Workstations are assigned with IP addresses in the 169.254.0.0/16 network.

Answer explanation

When workstations are configured with obtaining IP address automatically but DHCP servers are not available to respond to the requests, a workstation can assign itself an IP addresses from the 169.254.0.0/16 network.

Front

What is one indication that a Windows computer did not receive an IPv4 address from a DHCP server? Options: The computer cannot ping 127.0.0.1., Windows displays a DHCP timeout message., The computer receives an IP address that starts with 169.254., The computer cannot ping other devices on the same network with IP addresses in the 169.254.0.0/16 range.

Back

The computer receives an IP address that starts with 169.254.

Answer explanation

When a Windows PC cannot communicate with an IPv4 DHCP server, the computer automatically assigns an IP address in the 169.254.0.0/16 range. Any other device on the same network that receives an address in the same range is reachable.​