CCNA2 Module 3 (Netacad Module 7)

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?

255.255.255.255

What is the destination IP address when an IPv4 host sends a DHCPDISCOVER message?

255.255.255.255

What is DHCP ACK?

A DCHP frame sent out to acknowledge a clients request for and acceptance of an IP address. When sent an IP is configured on the client.

What is DHCP Offer?

A advertisement sent out by a DHCP server to respond to a Discover request, which contains an available IP address.

What is DHCP Discover?

A broadcast frame with its own MAC address sent out to identify DHCP servers on a network.

What is a DHCP request?

A frame that a client sends to a DHCP server to accept an offered address.

What is DHCP (Dynamic Host Configuration Protocol)?

A protocol used to automate the assignment of IP Addresses. It stands for Dynamic Host Control Protocol and is the successor to BOOTP.

How does DHCP work?

DHCP Discover (DHCPDISCOVER) DHCP Offer (DHCPOFFER) DHCP Request (DHCPREQUEST) DHCP Acknowledgment (DHCPACK)

What are the 2 steps for DHCP lease renewal?

DHCP Request (DHCPREQUEST) Before the lease expires, the client sends a DHCPREQUEST message directly to the DHCPv4 server that originally offered the IPv4 address. If a DHCPACK is not received within a specified amount of time, the client broadcasts another DHCPREQUEST so that one of the other DHCPv4 servers can extend the lease. DHCP Acknowledgment (DHCPACK) On receiving the DHCPREQUEST message, the server verifies the lease information by returning a DHCPACK.

What is the purpose of a DHCP lease?

DHCP manages a finite pool of IP addresses that it assigns on demand. By leasing addresses for a specific time period only, it is able to reclaim addresses of hosts that do not renew their lease.

Which DHCP IPv4 message contains the following information? Destination address: 255.255.255.255Client IPv4 address: 0.0.0.0Default gateway address: 0.0.0.0Subnet mask: 0.0.0.0

DHCPDISCOVER

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? (Choose two.) DHCPNAK DHCPDISCOVER DHCPREQUEST DHCPOFFER DHCPACK

DHCPDISCOVER DHCPREQUEST

What kind of message is sent by a DHCPv4 client requesting an IP address?

DHCPDISCOVER broadcast message

As a DHCPv4 client lease is about to expire, what is the message that the client sends the DHCP server?

DHCPREQUEST

Which is a DHCPv4 address allocation method that assigns IPv4 addresses for a limited lease period?

Dynamic allocation

What is the most likely scenario in which the WAN interface of a router would be configured as a DHCP client to be assigned a dynamic IP address from an ISP?

It is a SOHO or home broadband router

What services can a router be configured to relay?

Port 37: Time Port 49: TACACS Port 53: DNS Port 67: DHCP/BOOTP server Port 68: DHCP/BOOTP client Port 69: TFTP Port 137: NetBIOS name service Port 138: NetBIOS datagram service

What is the command syntax to exclude IPv4 addresses?

R1(config)# ip dhcp excluded-address Low-address [high-address]

What commands are used to disable a Cisco IOS DHCPv4 server?

R1(config)# no service dhcp R1(config)# service dhcp

What is the command syntax to define a address pool name?

Router(config)# ip dhcp pool pool-name Router(dhcp-config)#

Under which two circumstances would a router usually be configured as a DHCPv4 client? (Choose two.)

SOHO routers are frequently required by the ISP to be configured as DHCPv4 clients in order to be connected to the provider.

What steps are used to configure a Cisco router as a DHCP server?

Step 1. Exclude IPv4 addresses. Step 2. Define a DHCPv4 pool name. Step 3. Configure the DHCPv4 pool.

How is a DHCPDISCOVER transmitted on a network to reach a DHCP server?

The DHCPDISCOVER message is sent by a DHCPv4 client and targets a broadcast IP along with the destination port 67. The DHCPv4 server or servers respond to the DHCPv4 clients by targeting port 68.

What is the reason why the DHCPREQUEST message is sent as a broadcast during the DHCPv4 process?

The DHCPREQUEST message is broadcast to inform other DHCP servers that an IP address has been leased.

What does the ip helper-address do?

cause the router to relay DHCPv4 broadcasts to the DHCPv4 server.

What does the lease command do?

changes the duration of the DHCP lease

Which address does a DHCPv4 server target when sending a DHCPOFFER message to a client that makes an address request?

client hardware address

What mode does DHCP work in?

client/server mode

What does the dns-server command do?

configures the IPv4 address for the DNS server that is available to the DHCPv4 client.

An administrator issues the commands: Router(config)# interface g0/1Router(config-if)# ip address dhcp What is the administrator trying to achieve?

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

What does the domain-name command do?

defines the domain name

If more than one DHCP server is available on the local network, in which order will DHCP messages be sent between a host and a DHCP server?

discover, offer, request, acknowledgement

How do you configure a router to be a DHCPv4 relay agent?

ip helper-address

What commands are required to configure the DHCPv4 pool?

network- define range of available addresses default-router- define default gateway router

what commands are used to verify the Cisco IOS DHCPv4 server is operational?

show running-config | section dhcp-Displays the DHCPv4 commands configured on the router. show ip dhcp binding-Displays a list of all IPv4 address to MAC address bindings provided by the DHCPv4 service. show ip dhcp server statistics-Displays count information regarding the number of DHCPv4 messages that have been sent and received.

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

Why must some ip addresses be excluded from the DHCP pool?

some IPv4 addresses in a pool are assigned to network devices that require static address assignments. Therefore, these IPv4 addresses should not be assigned to other devices. Excluded addresses should be those addresses that are assigned to routers, servers, printers, and other devices that have been, or will be, manually configured.

What does the netbios-name-server command do?

used to define the NetBIOS WINS server.