CCNAv2 7-9 Exam PREP

A DHCP-enabled client PC has just booted. During which two steps will the client PC use broadcast messages when communicating with a DHCP server?

• DHCPDISCOVER

• DHCPACK

• DHCPOFFER

• DHCPREQUEST

• DHCPNAK

Answer explanation

Explanation: All DHCP messages between a DHCP-enabled client and a DHCP server are using broadcast messages until after the DHCPACK message. The DHCPDISCOVER and DHCPREQUEST messages are the only messages that are sent by a DHCP-enabled client. All DHCP messages between a DHCP-enabled client and a DHCP server use broadcast messages when the client is obtaining a lease for the first time.

An administrator issues the commands:

Router(config)# interface g0/1

Router(config-if)# ip address dhcp

What is the administrator trying to achieve?

• configuring the router to act as a DHCPv4 server

• configuring the router to obtain IP parameters from a DHCPv4 server

• configuring the router to act as a relay agent

• configuring the router to resolve IP address conflicts

When a client is requesting an initial address lease from a DHCP server, why is the DHCPREQUEST message sent as a broadcast?

• The client does not yet know the IP address of the DHCP server that sent the offer.

• The DHCP server may be on a different subnet, so the request must be sent as a broadcast.

• The client does not have a MAC address assigned yet, so it cannot send a unicast message at Layer 2.

• The client may have received offers from multiple servers, and the broadcast serves to implicitly decline those other offers.

Answer explanation

Explanation: During the initial DHCP exchange between a client and server, the client broadcasts a DHCPDISCOVER message looking for DHCP servers. Multiple servers may be configured to respond to this request with DHCPOFFER messages. The client will choose the lease from one of the servers by sending a DHCPREQUEST message. It sends this message as a broadcast so that the other DHCP servers that sent offers will know that their offers were declined and the corresponding address can go back into the pool.

Which DHCP IPv4 message contains the following information?

Destination address: 255.255.255.255

Client IPv4 address: 0.0.0.0

Default gateway address: 0.0.0.0

Subnet mask: 0.0.0.0

• DHCPACK

• DHCPDISCOVER

• DHCPOFFER

• DHCPREQUEST

1a) What is the first step in the DHCP process between a client and a server?

• a client initiating a message to find a DHCP server – DHCPDISCOVER

• a DHCP server responding to the initial request by a client – DHCPOFFER

• the client accepting the IP address provided by the DHCP server – DHCPREQUEST

• the DHCP server confirming that the lease has been accepted – DHCPACK

Answer explanation

Explanation: The DHCPDISCOVER message is used to identify any DHCP servers on a network.

The DHCPOFFER message is used by a server to offer a lease to a client.

The DHCPREQUEST message is used to identify both the specific DHCP server and the lease that the client is accepting.

The DHCPACK message is used by a server to finalize a successful lease with a client.

The DHCPNAK message is used when an offered lease is no longer valid.

1b) What is the second step in the DHCP process between a client and a server?

• a client initiating a message to find a DHCP server – DHCPDISCOVER

• a DHCP server responding to the initial request by a client – DHCPOFFER

• the client accepting the IP address provided by the DHCP server – DHCPREQUEST

• the DHCP server confirming that the lease has been accepted – DHCPACK

Answer explanation

Explanation: The DHCPDISCOVER message is used to identify any DHCP servers on a network.

The DHCPOFFER message is used by a server to offer a lease to a client.

The DHCPREQUEST message is used to identify both the specific DHCP server and the lease that the client is accepting.

The DHCPACK message is used by a server to finalize a successful lease with a client.

The DHCPNAK message is used when an offered lease is no longer valid.

1c) What is the third step in the DHCP process between a client and a server?

• a client initiating a message to find a DHCP server – DHCPDISCOVER

• a DHCP server responding to the initial request by a client – DHCPOFFER

• the client accepting the IP address provided by the DHCP server – DHCPREQUEST

• the DHCP server confirming that the lease has been accepted – DHCPACK

Answer explanation

Explanation: The DHCPDISCOVER message is used to identify any DHCP servers on a network.

The DHCPOFFER message is used by a server to offer a lease to a client.

The DHCPREQUEST message is used to identify both the specific DHCP server and the lease that the client is accepting.

The DHCPACK message is used by a server to finalize a successful lease with a client.

The DHCPNAK message is used when an offered lease is no longer valid.

1d) what is the fourth step in the DHCP process between a client and a server?

• a client initiating a message to find a DHCP server – DHCPDISCOVER

• a DHCP server responding to the initial request by a client – DHCPOFFER

• the client accepting the IP address provided by the DHCP server – DHCPREQUEST

• the DHCP server confirming that the lease has been accepted – DHCPACK

Answer explanation

Explanation: The DHCPDISCOVER message is used to identify any DHCP servers on a network.

The DHCPOFFER message is used by a server to offer a lease to a client.

The DHCPREQUEST message is used to identify both the specific DHCP server and the lease that the client is accepting.

The DHCPACK message is used by a server to finalize a successful lease with a client.

The DHCPNAK message is used when an offered lease is no longer valid.

Which protocol automates assignment of IP addresses on a network, and which port number does it use? (Choose two.)

• DHCP

• DNS

• SMB

• 53

• 67

Answer explanation

Explanation: DNS uses port 53 and translates URLs to IP addresses. SMB provides shared access to files and printers and uses port 445. Port 80 is used by HTTP. HTTP is a protocol used to communicate between a web browser and a server.

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?

• 192.168.1.1

• 192.168.1.255

• 192.168.1.8

• 255.255.255.255

Answer explanation

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.