Cisco 351-001 Online Practice Questions and Exam Preparation

Cisco 351-001 Online Questions & Answers

• Question 141:

  Refer to the exhibit.

  

  Which two statements about this CoS mapping are true? (Choose two)

  A. It maps the second queue and first threshold to CoS 2.
  B. It maps the first queue and first threshold to CoS 2 and CoS 3.
  C. It maps CoS values to the transmit queue threshold.
  D. It maps the second threshold to CoS and CoS 3.
  E. It maps the second queue and first threshold to CoS 3.
  C. It maps CoS values to the transmit queue threshold.
  D. It maps the second threshold to CoS and CoS 3.

• Question 142:

  Refer to the exhibit.

  

  All of the routers on this network are running RIP. If you edit the R3 RIP process configuration to reduce the number of hops from R3 to R1, which statement about the configuration change is true?

  A. Configuring no passive-interface for GigabitEthernet0/0 in the R3 RIP process reduces the number of hops to R1 by 2.
  B. Configuring no passive-interface for GigabitEthernet0/0 in the R3 RIP process reduces the number of hops to R1 by 1.
  C. Configuring no passive-interface for GigabitEthernet0/1 in the R3 RIP process reduces the number of hops to R1 by 3.
  D. Configuring no passive-interface for GigabitEthernet0/1 in the R3 RIP process reduces the number of hops to R1 by 1.
  A. Configuring no passive-interface for GigabitEthernet0/0 in the R3 RIP process reduces the number of hops to R1 by 2.

  ---

  By changing the link from R3 to R2 to not be passive, traffic can then take the direct route from R3-R2-R1 instead of the longer path of R3-R6-R5-R4-R1, resulting in two less hops.

• Question 143:

  What is a cause for unicast flooding?

  A. Unicast flooding occurs when multicast traffic arrives on a Layer 2 switch that has directly connected multicast receivers.
  B. When PIM snooping is not enabled, unicast flooding occurs on the switch that interconnects the PIM-enabled routers.
  C. A man-in-the-middle attack can cause the ARP cache of an end host to have the wrong MAC address. Instead of having the MAC address of the default gateway, it has a MAC address of the man-in-the-middle. This causes all traffic to be unicast flooded through the man-in-the-middle, which can then sniff all packets.
  D. Forwarding table overflow prevents new MAC addresses from being learned, and packets destined to those MAC addresses are flooded until space becomes available in the forwarding table.
  D. Forwarding table overflow prevents new MAC addresses from being learned, and packets destined to those MAC addresses are flooded until space becomes available in the forwarding table.

  ---

  Causes of Flooding The very cause of flooding is that destination MAC address of the packet is not in the L2 forwarding table of the switch. In this case the packet will be flooded out of all forwarding ports in its VLAN (except the port it was received on). Below case studies display most common reasons for destination MAC address not being known to the switch. Cause 1: Asymmetric Routing Large amounts of flooded traffic might saturate low-bandwidth links causing network performance issues or complete connectivity outage to devices connected across such low-bandwidth links Cause 2: Spanning-Tree Protocol Topology Changes Another common issue caused by flooding is Spanning-Tree Protocol (STP) Topology Change Notification (TCN). TCN is designed to correct forwarding tables after the forwarding topology has changed. This is necessary to avoid a connectivity outage, as after a topology change some destinations previously accessible via particular ports might become accessible via different ports. TCN operates by shortening the forwarding table aging time, such that if the address is not relearned, it will age out and flooding will occur Cause 3: Forwarding Table Overflow Another possible cause of flooding can be overflow of the switch forwarding table. In this case, new addresses cannot be learned and packets destined to such addresses are flooded until some space becomes available in the forwarding table. New addresses will then be learned. This is possible but rare, since most modern switches have large enough forwarding tables to accommodate MAC addresses for most designs.

  Reference: http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6000-series-switches/23563- 143.html

• Question 144:

  Refer to the exhibit.

  

  What is the role of this multicast router?

  A. a first-hop PIM router
  B. a last-hop PIM router
  C. a PIM rendezvous point
  D. a PIM inter-AS router
  C. a PIM rendezvous point

  ---

  The following is sample output from the show ip pim tunnel taken from an RP. The output is used to verify the PIM Encap and Decap Tunnel on the RP:

  Switch# show ip pim tunnel

  Tunnel0

  Type : PIM Encap

  RP : 70.70.70.1*

  SourcE. 70.70.70.1

  Tunnel1*

  Type : PIM Decap

  RP : 70.70.70.1*

  SourcE. -R2#

  The asterisk (*) indicates that the router is the RP. The RP will always have a PIM Encap and Decap Tunnel interface.

  Reference:

  http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3650/software/release/3se/multic ast/command_reference/b_mc_3se_3650_cr/ b_mc_3se_3650_cr_chapter_010.html#wp12 86920037

• Question 145:

  Refer to the exhibit.

  

  You are bringing a new MPLS router online and have configured only what is shown to bring LDP up. Assume that the peer has been configured in a similar manner. You verify the LDP peer state and see that there are no neighbors. What will the output of show mpls ldp discovery show?

  A. Interfaces: Ethernet0/0 (ldp): xmit
  B. Interfaces: Ethernet0/0 (ldp): xmit/recv LDP Id: 25.25.25.2:0; IP addr: 192.168.12.2
  C. Interfaces: Ethernet0/0 (ldp): xmit/recv LDP Id: 192.168.12.2:0; no route
  D. Interfaces: Ethernet0/0 (ldp): xmit/recv LDP Id: 25.25.25.2:0; no route
  D. Interfaces: Ethernet0/0 (ldp): xmit/recv LDP Id: 25.25.25.2:0; no route

• Question 146:

  Which Cisco PfR monitoring mode is recommended for Internet edge deployments?

  A. active mode
  B. active throughput mode
  C. fast mode
  D. passive mode
  D. passive mode

• Question 147:

  DRAG DROP

  Drag and drop the multiprotocol BGP feature on the left to the corresponding description on the right.

  Select and Place:

  

  

• Question 148:

  Which option is the default maximum age of the MAC address table?

  A. 300 seconds
  B. 500 seconds
  C. 1200 seconds
  D. 3600 seconds
  A. 300 seconds

  ---

  To configure the maximum aging time for entries in the Layer 2 table, use the mac- address-table aging-time command in global configuration mode.

  Syntax Description

  seconds

  MAC address table entry maximum age. Valid values are 0, and from 5 to 1000000 seconds. Aging time is counted from the last time that the switch detected the MAC address. The default value is 300 seconds.

  Reference:

  http://www.cisco.com/c/en/us/td/docs/ios/lanswitch/command/reference/lsw_book/lsw_m1.

  html

• Question 149:

  Which option is the Cisco recommended method to secure access to the console port?

  A. Configure the activation-character command.
  B. Configure a very short timeout (less than 100 milliseconds) for the port.
  C. Set the privilege level to a value less than 15.
  D. Configure an ACL.
  A. Configure the activation-character command.

  ---

  The activation-character command defines a session activation character. Entering this character at a vacant terminal begins a terminal session. The default activation character is the Return key To secure the console port, you should change this character to a different one as most people simply hit the enter key when trying to access the console.

• Question 150:

  Which feature can segregate routing tables on a single device?

  A. BGP
  B. VRF-lite
  C. OSPFv3
  D. MPLS
  B. VRF-lite