Test 9 - CCNA 2

Which sequence correctly identifies the order of the steps that a router will perform when it receives a packet on an Ethernet interface?

• 1. The router examines the destination MAC address.
  2. The router identifies the Ethernet Type field.
  3. The router de-encapsulates the Ethernet frame.
  4. The router examines the destination IP address.

• 1. The router de-encapsulates the Ethernet frame.
  2. The router examines the destination MAC address.
  3. The router identifies the Ethernet Type field.
  4. The router examines the destination IP address.

• 1. The router examines the destination IP address.
  2. The router examines the destination MAC address.
  3. The router identifies the Ethernet Type field.
  4. The router de-encapsulates the Ethernet frame.

• 1. The router examines the destination MAC address.
  2. The router identifies the Ethernet Type field.
  3. The router examines the destination IP address.
  4. The router de-encapsulates the Ethernet frame.

• 1. The router examines the destination IP address.
  2. The router examines the destination MAC address.
  3. The router de-encapsulates the Ethernet frame.
  4. The router identifies the Ethernet Type field.

Answer explanation

Explanation: When a router receives a packet the first thing that happens is the destination MAC address is checked to verify that the rest of the packet should be processed. Assuming the destination MAC address matches the address on the router interface, the Ethernet Type field is checked to determine what Layer 3 protocol is encapsulated in the frame. The frame is then de-encapsulated and the destination IP address is examined to determine where the packet should be sent.

Which three IOS troubleshooting commands can help to isolate problems with a static route? (Choose three.)

• show version

• show arp

• show ip interface brief

• show ip route

• ping

Answer explanation

Explanation: The ping, show ip route, and show ip interface brief commands provide information to help troubleshoot static routes. Show version does not provide any routing information. The tracert command is used at the Windows command prompt and is not an IOS command. The show arp command displays learned IP address to MAC address mappings contained in the Address Resolution Protocol (ARP) table.

A static route has been configured on a router. However, the destination network no longer exists. What should an administrator do to remove the static route from the routing table?

• Remove the route using the no ip route command.

• Change the routing metric for that route.

• Change the administrative distance for that route.

• Nothing. The static route will go away on its own.

Answer explanation

Explanation: When the destination network specified in a static route does not exist anymore, the static route stays in the routing table until it is manually removed by using the no ip route command.

A network engineer issues the show cdp neighbor command on several network devices during the process of network documentation. What is the purpose of performing this command?

• to verify the network addresses that are attached to the network devices

• to obtain information about directly connected Cisco devices

• to check the networks that are advertised by the neighboring routers

• to check the connectivity of PCs that are connected to the network devices

Answer explanation

Explanation: The show cdp neighbor command is used to obtain detailed information about directly connected Cisco devices. The information does not include which networks are attached to the neighboring Cisco devices nor the connectivity of PCs that are attached to them. The show ip route command is used to view the networks that are advertised from neighboring routers.

A network administrator has entered the following command:

ip route 192.168.10.64 255.255.255.192 serial0/0/1

When the network administrator enters the command show ip route, the route is not in the routing table. What should the administrator do next?

• Re-enter the command using the correct mask.

• Re-enter the command using a network number rather than a usable IP address.

• Verify that the serial 0/0/1 interface is active and available.

• Verify that the 192.168.10.64 network is active within the network infrastructure.

Answer explanation

Explanation: The reason that a correctly typed static network would not go into the routing table is if the exit interface is not available. The 192.168.10.64 is a valid network number and that route does not have to be “up and up” in order for a static route to be configured on a remote router.

What will a router do if it does not have a default route configured and a packet needs to be forwarded to a destination network that is not listed in the routing table?

• send it back to the source

• drop it

• forward it to another router

Answer explanation

Explanation: A router will only forward packets if it has the destination network in its routing table. If it receives a packet with a destination network that is not in the routing table, the router will drop it. A default route can be installed on a router to make the router forward packets to another router that can route the packet to its destination.

What does the letter C mean next to an entry in the output of the show ip route command?

• It identifies a network that is learned through EIGRP.

• It identifies a network that is directly connected to the router.

• It identifies a network that is learned through OSPF.

• It identifies a network that is a static route.

Answer explanation

Explanation: In a routing table, the label C identifies a network that is directly connected to an interface on the device. This entry is added to the routing table when an interface is configured with an IP address and activated.

What happens to a static route entry in a routing table when the outgoing interface associated with that route goes into the down state?

• The router automatically redirects the static route to use another interface.

• The router polls neighbors for a replacement route.

• The static route is removed from the routing table.

• The static route remains in the table because it was defined as static.

Answer explanation

Explanation: When the interface associated with a static route goes down, the router will remove the route because it is no longer valid.

What action will a router take to forward a frame if it does not have an entry in the ARP table to resolve a destination MAC address?

• Sends a DNS request

• Drops the frame

• Sends an ARP request

• Sends frame to the default gateway

Answer explanation

Explanation: A router looks up the ARP table entry for the destination IP address to find the Layer 2 Media Access Control (MAC) address of the host. If no entry exists, the router sends an Address Resolution Protocol (ARP) request out of network interface, and the host responds with an ARP reply, which includes its MAC address.