Cisco 351-001 Online Practice Questions and Exam Preparation

Cisco 351-001 Online Questions & Answers

• Question 991:

  Which statement about the NHRP network ID is true?

  A. It is sent from the spoke to the hub to identify the spoke as a member of the same NHRP domain.
  B. It is sent from the hub to the spoke to identify the hub as a member of the same NHRP domain.
  C. It is sent between spokes to identify the spokes as members of the same NHRP domain.
  D. It is a locally significant ID used to define the NHRP domain for an interface.
  D. It is a locally significant ID used to define the NHRP domain for an interface.

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  The NHRP network ID is used to define the NHRP domain for an NHRP interface and differentiate between multiple NHRP domains or networks, when two or more NHRP domains (GRE tunnel interfaces) are available on the same NHRP node (router). The NHRP network ID is used to help keep two NHRP networks (clouds) separate from each other when both are configured on the same router. The NHRP network ID is a local only parameter. It is significant only to the local router and it is not transmitted in NHRP packets to other NHRP nodes. For this reason the actual value of the NHRP network ID configured on a router need not match the same NHRP network ID on another router where both of these routers are in the same NHRP domain. As NHRP packets arrive on a GRE interface, they are assigned to the local NHRP domain in the NHRP network ID that is configured on that interface.

  Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_4/ip_addr/configuration/guide/hadnhrp.html

• Question 992:

  What is the cause of ignores and overruns on an interface, when the overall traffic rate of the interface is low?

  A. a hardware failure of the interface
  B. a software bug
  C. a bad cable
  D. microbursts of traffic
  D. microbursts of traffic

  ---

  Micro-bursting is a phenomenon where rapid bursts of data packets are sent in quick succession, leading to periods of full line-rate transmission that can overflow packet buffers of the network stack, both in network endpoints and routers and switches inside the network. Symptoms of micro bursts will manifest in the form of ignores and/ or overruns (also shown as accumulated in "input error" counter within show interface output). This is indicative of receive ring and corresponding packet buffer being overwhelmed due to data bursts coming in over extremely short period of time (microseconds). You will never see a sustained data traffic within show interface's "input rate" counter as they are averaging bits per second (bps) over 5 minutes by default (way too long to account for microbursts). You can understand microbursts from a scenario where a 3-lane highway merging into a single lane at rush hour ?the capacity burst cannot exceed the total available bandwidth (i.e. single lane), but it can saturate it for a period of time.

  Reference: http://ccieordie.com/?tag=micro-burst

• Question 993:

  Which two statements are true about VPLS? (Choose two.)

  A. It can work over any transport that can forward IP packets.
  B. It provides integrated mechanisms to maintain First Hop Resiliency Protocols such as HSRP, VRRP, or GLBP.
  C. It includes automatic detection of multihoming.
  D. It relies on flooding to propagate MAC address reachability information.
  E. It can carry a single VLAN per VPLS instance.
  D. It relies on flooding to propagate MAC address reachability information.
  E. It can carry a single VLAN per VPLS instance.

  ---

  VPLS relies on flooding to propagate MAC address reachability information. Therefore, flooding cannot be prevented. VPLS can carry a single VLAN per VPLS instance. To multiplex multiple VLANs on a single instance, VPLS uses IEEE QinQ.

  Reference: http://www.cisco.com/c/en/us/products/collateral/switches/nexus-7000-series- switches/white_paper_c11-574984.html

• Question 994:

  Which two statements about the client-identifier in a DHCP pool are true? (Choose two.)

  A. It specifies a unique identifier that is used only for DHCP requests.
  B. It is specified by appending 01 to the MAC address of a DHCP client.
  C. It specifies a hardware address for the client.
  D. It specifies a unique identifier that is used only for BOOTP requests.
  E. It requires that you specify the hardware protocol.
  A. It specifies a unique identifier that is used only for DHCP requests.
  B. It is specified by appending 01 to the MAC address of a DHCP client.

  ---

  Reference:

  client-identifier unique-identifier

  Example:

  Device(dhcp-config)# client-identifier 01b7.0813.8811.66

  Specifies the unique identifier for DHCP clients.

  This command is used for DHCP requests.

  DHCP clients require client identifiers. You can specify the unique identifier for the client in either of the following ways:

  A 7-byte dotted hexadecimal notation. For example, 01b7.0813.8811.66, where 01 represents the Ethernet media type and the remaining bytes represent the MAC address of the DHCP client.

  A 27-byte dotted hexadecimal notation. For example, 7665.6e64.6f72.2d30.3032.342e.3937.6230.2e33.3734.312d.4661.302f.31. The equivalent ASCII string for this hexadecimal value is vendor-0024.97b0.3741-fa0/1, where vendor

  represents the vendor, 0024.97b0.3741 represents the MAC address of the source interface, and fa0/1 represents the source interface of the DHCP client.

  See the Troubleshooting Tips section for information about how to determine the client identifier of the DHCP client.

  Note

  The identifier specified here is considered for a DHCP client that sends a client identifier in the packet.

  Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/15- mt/dhcp-15-mt-book/config-dhcp-server.html

• Question 995:

  Which type of port would have root guard enabled on it?

  A. A root port
  B. An alternate port
  C. A blocked port
  D. A designated port
  D. A designated port

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  The root guard feature provides a way to enforce the root bridge placement in the network. The root guard ensures that the port on which root guard is enabled is the designated port. Normally, root bridge ports are all designated ports, unless two or more ports of the root bridge are connected together. If the bridge receives superior STP Bridge Protocol Data Units (BPDUs) on a root guard-enabled port, root guard moves this port to a root- inconsistent STP state. This root-inconsistent state is effectively equal to a listening state. No traffic is forwarded across this port. In this way, the root guard enforces the position of the root bridge.

  Reference: http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree- protocol/10588-74.html

• Question 996:

  Which statement about MSS is true?

  A. It is negotiated between sender and receiver.
  B. It is sent in all TCP packets.
  C. It is 20 bytes lower than MTU by default.
  D. It is sent in SYN packets.
  E. It is 28 bytes lower than MTU by default.
  D. It is sent in SYN packets.

  ---

  The maximum segment size (MSS) is a parameter of the Options field of the TCP header that specifies the largest amount of data, specified in octets, that a computer or communications device can receive in a single TCP segment. It does not count the TCP header or the IP header. The IP datagram containing a TCP segment may be self- contained within a single packet, or it may be reconstructed from several fragmented pieces; either way, the MSS limit applies to the total amount of data contained in the final, reconstructed TCP segment. The default TCP Maximum Segment Size is 536. Where a host wishes to set the maximum segment size to a value other than the default, the maximum segment size is specified as a TCP option, initially in the TCP SYN packet during the TCP handshake. The value cannot be changed after the connection is established.

  Reference: http://en.wikipedia.org/wiki/Maximum_segment_size