Cisco 351-001 Online Practice Questions and Exam Preparation

Cisco 351-001 Online Questions & Answers

• Question 531:

  Which congestion-avoidance or congestion-management technique can cause global synchronization?

  A. Tail drop
  B. Random early detection
  C. Weighted random early detection
  D. Weighted fair queuing
  A. Tail drop

  ---

  Tail Drop

  Tail drop treats all traffic equally and does not differentiate between classes of service. Queues fill during periods of congestion. When the output queue is full and tail drop is in effect, packets are dropped until the congestion is eliminated and

  the queue is no longer full.

  Weighted Random Early Detection

  WRED avoids the globalization problems that occur when tail drop is used as the congestion avoidance mechanism on the router. Global synchronization occurs as waves of congestion crest only to be followed by troughs during which the

  transmission link is not fully utilized. Global synchronization of TCP hosts, for example, can occur because packets are dropped all at once. Global synchronization manifests when multiple TCP hosts reduce their transmission rates in

  response to packet dropping, then increase their transmission rates once again when the congestion is reduced.

  Reference:

  http://www.cisco.com/c/en/us/td/docs/ios/12_2/qos/configuration/guide/fqos_c/qcfconav.ht ml#wp1002048

• Question 532:

  Which two statements about marking fields are true? (Choose two)

  A. The IP Precedence field is in the IP header and is 4 bits long.
  B. The Frame Relay DE field is in the IP header and is 1 bit long.
  C. The 3 priority bits are in 802.1Q/P.
  D. The IP DSCP field is in the IP header and is 6 bits long.
  E. The ToS 6 bits are in the IP header.
  C. The 3 priority bits are in 802.1Q/P.
  D. The IP DSCP field is in the IP header and is 6 bits long.

• Question 533:

  Which type of OSPF packet is an OSPF link state update packet?

  A. type 1
  B. type 2
  C. type 3
  D. type 4
  E. type 5
  D. type 4

  ---

  Link State Update packets are OSPF packet type 4. These packets implement the flooding of link state advertisements. Each Link State Update packet carries a collection of link state advertisements one hop further from its origin. Several link state advertisements may be included in a single packet.

  Reference: http://www.freesoft.org/CIE/RFC/1583/107.htm

• Question 534:

  Which two technologies are supported by EIGRP? (Choose two.)

  A. clear-text authentication
  B. MD5 authentication
  C. stub routing
  D. multiple areas
  B. MD5 authentication
  C. stub routing

  ---

  The IP Enhanced IGRP Route Authentication feature provides MD5 authentication of routing updates from the EIGRP routing protocol. The MD5 keyed digest in each EIGRP packet prevents the introduction of unauthorized or false routing

  messages from unapproved sources. The EIGRP stub routing feature improves network stability, reduces resource utilization, and simplifies the stub device configuration. Stub routing is commonly used in hub-and-spoke network topologies.

  In a hub-and-spoke network, one or more end (stub) networks are connected to a remote device (the spoke) that is connected to one or more distribution devices (the hub). The remote device is adjacent to one or more distribution devices.

  The only route for IP traffic to reach the remote device is through a distribution device.

  References:

  http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_eigrp/configuration/15-s/ire-15-s- book/ire-rte-auth.html http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_eigrp/configuration/15-s/ire-15-s- book/ire-eigrp-stub-rtg.html

• Question 535:

  What is the ip dhcp snooping information option command used for?

  A. It displays information about the DHCP snooping table.
  B. It sends a syslog and an SNMP trap for a DHCP snooping violation.
  C. It enables the DHCP snooping host tracking feature.
  D. It enables DHCP option 82 data insertion.
  D. It enables DHCP option 82 data insertion.

  ---

  To enable DHCP option-82 data insertion, perform this task:

  Command Purpose Step 1 Router(config)# ip dhcp snooping information option Enables DHCP option-82 data insertion. Step 2 Router(config)# ip dhcp snooping information option replace Or: Router(config-if)# ip dhcp snooping information option replace (Optional) Replaces the DHCP relay information option received in snooped packets with the switch's option-82 data. Step 3 Router(config)# do show ip dhcp snooping | include 82 Verifies

  Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12- 2SX/configuration/guide/book/snoodhcp.html

• Question 536:

  An IP SLA fails to generate statistics. How can you fix the problem?

  A. Add the verify-data command to the router configuration.
  B. Reload the router configuration.
  C. Remove the ip sla schedule statement from the router configuration and re-enter it.
  D. Add the debug ip sla error command to the router configuration.
  E. Add the debug ip sla trace command to the router configuration.
  A. Add the verify-data command to the router configuration.

• Question 537:

  Refer to the exhibit.

  

  Which statement is true?

  A. R1 routes this pseudowire over MPLS TE tunnel 1 with transport label 20.
  B. The default route 0.0.0.0/0 is available in the IPv4 routing table.
  C. R1 is using an MPLS TE tunnel for this pseudowire, because the IP path is not available.
  D. R1 has preferred-path configured for the pseudowire.
  D. R1 has preferred-path configured for the pseudowire.

  ---

  Verifying the Configuration: Example

  In the following example, the show mpls l2transport vc command shows the following information (in bold) about the VCs:

  ?

  VC 101 has been assigned a preferred path called Tunnel1. The default path is disabled because the preferred path specified that the default path should not be used if the

  ?

  VC 150 has been assigned an IP address of a loopback address on PE2. The default path can be used if the preferred path fails.

  Router# show mpls l2transport vc detail

  Local interface. Gi0/0/0.1 up, line protocol up, Eth VLAN 222 up Destination address: 10.16.16.16, VC ID. 101, VC status: up Preferred path: Tunnel1, active Default path: disabled

  Tunnel label: 3, next hop point2point

  Output interfacE. Tu1, imposed label stack {17 16} Create timE. 00:27:31, last status change timE. 00:27:31 Signaling protocol: LDP, peer 10.16.16.16:0 up MPLS VC labels: local 25, remote 16 Group ID. local 0, remote 6 MTU: local 1500, remote 1500 Remote interface description: Sequencing: receive disabled, send disabled VC statistics: packet totals: receive 10, send 10 byte totals: receive 1260, send 1300 packet drops: receive 0, send 0

  Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_2sr/12_2sra/feature/guide/srtunsel.html#wp10 57815

• Question 538:

  In an STP domain, which two statements are true for a nonroot switch, when it receives a configuration BPDU from the root bridge with the TC bit set? (Choose two.)

  A. It sets the MAC table aging time to max_age + forward_delay time.
  B. It sets the MAC table aging time to forward_delay time.
  C. It recalculates the STP topology upon receiving topology change notification from the root switch.
  D. It receives the topology change BPDU on both forwarding and blocking ports.
  B. It sets the MAC table aging time to forward_delay time.
  D. It receives the topology change BPDU on both forwarding and blocking ports.

  ---

  When the TC bit is received, every bridge is then notified and reduces the aging time to forward_delay (15 seconds by default) for a certain period of time (max_age + forward_delay). It is more beneficial to reduce the aging time instead of

  clearing the table because currently active hosts, that effectively transmit traffic, are not cleared from the table.

  Once the root is aware that there has been a topology change event in the network, it starts to send out its configuration BPDUs with the topology change (TC) bit set. These BPDUs are relayed by every bridge in the network with this bit set.

  As a result all bridges become aware of the topology change situation and it can reduce its aging time to forward_delay. Bridges receive topology change BPDUs on both forwarding and blocking ports. An important point to consider here is

  that a TCN does not start a STP recalculation. This fear comes from the fact that TCNs are often associated with unstable STP environments; TCNs are a consequence of this, not a cause. The TCN only has an impact on the aging time. It

  does not change the topology nor create a loop.

  Reference: http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree- protocol/12013-17.html

• Question 539:

  DRAG DROP

  Drag each routing protocol on the left to the matching statement on the right.

  Select and Place:

  

  

• Question 540:

  Which two methods does Cisco IOS XE use to implement separation between the data plane and control plane? (Choose two)

  A. the FED
  B. a Linux-based CPU scheduler to efficiently manage the control and data planes.
  C. separates FFM-spawned subshells in the Linux kernels for the control plane and the data plane.
  D. a set of APIs to manage data plane processes
  E. a set of APIs to manage control plane processes
  A. the FED
  E. a set of APIs to manage control plane processes