Cisco 351-001 Online Practice Questions and Exam Preparation

Cisco 351-001 Online Questions & Answers

• Question 41:

  What are two pieces of information that can be transmitted via Multiprotocol BGP? (Choose two)

  A. MPLS VPN routes
  B. Level 1/Level 2 routers set the overload-bit.
  C. multicast sources
  D. IS-IS LSAs
  E. Level 2 routers set the attached bit.
  F. OSPF routes
  A. MPLS VPN routes
  C. multicast sources

• Question 42:

  A GRE tunnel is down with the error message %TUN-5-RECURDOWN: Tunnel0 temporarily disabled due to recursive routing error. Which two options describe possible causes of the error? (Choose two.)

  A. Incorrect destination IP addresses are configured on the tunnel.
  B. There is link flapping on the tunnel.
  C. There is instability in the network due to route flapping.
  D. The tunnel mode and tunnel IP address are misconfigured.
  E. The tunnel destination is being routed out of the tunnel interface.
  C. There is instability in the network due to route flapping.
  E. The tunnel destination is being routed out of the tunnel interface.

  ---

  The %TUN-5-RECURDOWN: Tunnel0 temporarily disabled due to recursive routing error message means that the generic routing encapsulation (GRE) tunnel router has discovered a recursive routing problem. This condition is usually due to one of these causes: A misconfiguration that causes the router to try to route to the tunnel destination address using the tunnel interface itself (recursive routing) A temporary instability caused by route flapping elsewhere in the network

  Reference: http://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway- routing-protocol-eigrp/22327-gre-flap.html

• Question 43:

  Refer to the exhibit.

  

  While troubleshooting high CPU utilization on one of your Cisco Catalyst switches, you find that the issue is due to excessive flooding that is caused by STP. What can you do to prevent this issue from happening again?

  A. Disable STP completely on the switch.
  B. Change the STP version to RSTP.
  C. Configure PortFast on port-channel 1.
  D. Configure UplinkFast on the switch.
  E. Configure PortFast on interface Gi0/15.
  E. Configure PortFast on interface Gi0/15.

  ---

  Topology Changes (TC) should be a rare event in a well-configured network. When a link on a switch port goes up or down, there is eventually a TC, once the STP state of the port is changing to or from forwarding. When the port is flapping, this would cause repetitive TCs and flooding. Ports with the STP portfast feature enabled will not cause TCs when going to or from the forwarding state. The configuration of portfast on all end-device ports (such as printers, PCs, and servers) should limit TCs to a low amount and is highly recommended.

  Reference: http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree- protocol/28943-170.html

• Question 44:

  Which statement about VRRP is true?

  A. It supports load balancing.
  B. It can be configured with HSRP on a switch or switch stack.
  C. It supports IPv4 and IPv6.
  D. It supports encrypted authentication.
  B. It can be configured with HSRP on a switch or switch stack.

  ---

  VRRP Limitations

  You can configure both HSRP and VRRP on a switch or switch stack. However, you cannot add a switch model that supports only one protocol to a stack that is configured for both protocols.

  The VRRP implementation on the switch does not support the MIB specified in RFC 2787.

  The VRRP implementation on the switch supports only text -based authentication.

  The switch supports VRRP only for IPv4.

  Reference:

  http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/1 2-2_58_se/configuration/guide/3750xscg/swhsrp.html#pgfId-1107127

• Question 45:

  What is the function of an implicit-null label?

  A. It notifies the upstream LSR to remove the top label in the label stack and forward the packet.
  B. It notifies the upstream LSR to add a VPN label to the label stack.
  C. It is used to statically assign a label to an IGP route.
  D. It is used to identify the router ID.
  A. It notifies the upstream LSR to remove the top label in the label stack and forward the packet.

• Question 46:

  What are IPv6 addresses of the form FC00::/7 known as?

  A. unique local addresses
  B. transition addresses for 6to4
  C. link-local addresses
  D. multicast RP addresses
  A. unique local addresses

• Question 47:

  Which two conditions must be met by default to implement the BGP multipath feature? (Choose two.)

  A. The next-hop routers must be the same.
  B. Route reflectors must be enabled.
  C. All attributes must have the same values.
  D. MPLS must be enabled.
  E. The next-hop routers must be different.
  C. All attributes must have the same values.
  E. The next-hop routers must be different.

• Question 48:

  EIGRP allows configuration of multiple MD5 keys for packet authentication to support easy rollover from an old key to a new key. Which two statements are true regarding the usage of multiple authentication keys? (Choose two.)

  A. Received packets are authenticated by the key with the smallest key ID.
  B. Sent packets are authenticated by all valid keys, which means that each packet is replicated as many times as the number of existing valid keys.
  C. Received packets are authenticated by any valid key that is chosen.
  D. Sent packets are authenticated by the key with the smallest key ID.
  C. Received packets are authenticated by any valid key that is chosen.
  D. Sent packets are authenticated by the key with the smallest key ID.

  ---

  Suppose two routers are connected with each other via Fa0/0 interfaces and they are configured to authenticate via MD5. Below is a simple configuration on both routers so that they will work:

  Router1(config)#key chain KeyChainR1 Router1(config-keychain)#key 1 Router1(config-keychain-key)#key-string FirstKey Router1(config-keychain-key)#key 2 Router1(config-keychain-key)#key-string SecondKey Router2(config)#key chain KeyChainR2 Router2(config-keychain)#key 1 Router2(config-keychain-key)#key-string FirstKey Router2(config-keychain-key)#key 2 Router2(config-keychain-key)#key-string SecondKey

  Apply these key chains to R1 and R2:

  Router1(config)#interface fastEthernet 0/0 Router1(config-if)#ip authentication mode eigrp 1 md5 Router1(config-if)#ip authentication key-chain eigrp 1 KeyChainR1 Router2(config)#interface fastEthernet 0/0 Router2(config-if)#ip authentication mode eigrp 1 md5 Router2(config-if)#ip authentication key-chain eigrp 1 KeyChainR2

  There are some rules to configure MD5 authentication with EIGRP:

  + The key chain names on two routers do not have to match (in this case the name "KeyChainR1 and "KeyChainR2 do not match) + The key number and key-string on the two potential neighbors must match (for example "key 1 and "key-string

  FirstKey" must match on "key 1" and "key-string FirstKey" of neighboring router)

  Also some facts about MD5 authentication with EIGRP + When sending EIGRP messages the lowest valid key number is used -> D is correct. + When receving EIGRP messages all currently configured valid keys are verified but the lowest

  valid one will be used -> Although answer C does not totally mention like that but it is the most suitable answer because A and B are totally wrong. Answer A is not correct because we need valid key to authenticate. As mentioned above,

  although answer C is not totally correct but it puts some light on why answer B is not correct: each packet is NOT "replicated as many times as the number of existing valid keys". All currently configured valid keys are verified but the lowest

  valid one will be used.

• Question 49:

  Refer to the exhibit.

  

  Which two statements about the output are true? (Choose two.)

  A. 802.1D spanning tree is being used.
  B. Setting the priority of this switch to 0 for VLAN 1 would cause it to become the new root.
  C. The hello, max-age, and forward delay timers are not set to their default values.
  D. Spanning-tree PortFast is enabled on GigabitEthernet1/1.
  A. 802.1D spanning tree is being used.
  B. Setting the priority of this switch to 0 for VLAN 1 would cause it to become the new root.

  ---

  802.1D is the standard for Spanning tree, which is being used here. For priority, The priority order starts from 0 (yes, 0 is valid) and then increases in 4096.

  0, 4096, 8192, 12288, .... Etc.

  The lower the number is, the higher is the priority. Here we see that the current root has a priority of 8192, so configuring this with a priority of 0 will make it the new root.

• Question 50:

  Which two statements about IS-IS wide metrics are true? (Choose two.)

  A. The wide metric is a 24-bit field.
  B. The maximum link metric is 16777215.
  C. R3 and R4 periodically advertise PNSP messages to synchronize the IS-IS database.
  D. IS-IS devices that are enabled with wide metrics can become neighbors with a device that uses standard metrics.
  E. The maximum link metric is 4261412864.
  F. The maximum path metric is 16777215.
  A. The wide metric is a 24-bit field.
  B. The maximum link metric is 16777215.