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Cisco ENCOR 350-401 Exam Questions and Answers – Page 3

The latest Cisco CCNP and CCIE Enterprise Core: Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) 350-401 certification actual real practice exam question and answer (Q&A) dumps are available free, which are helpful for you to pass the Cisco CCNP and CCIE Enterprise Core: Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) 350-401 exam and earn Cisco CCNP and CCIE Enterprise Core: Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) 350-401 certification.

Exam Question 211

You administer the networks shown above. RouterA is connected to network A, RouterB is connected to network B, and so on. RouterB and RouterD are iBGP peers of RouterC; RouterE and RouterF are eBGP peers of RouterC. RouterA and RouterC are OSPF neighbors.

You administer the networks shown above. RouterA is connected to network A, RouterB is connected to network B, and so on. RouterB and RouterD are iBGP peers of RouterC; RouterE and RouterF are eBGP peers of RouterC. RouterA and RouterC are OSPF neighbors.
RouterC, which is not configured as a route reflector, receives routes from all of the other routers on the network. You have issued the network command on each router to advertise their respective networks. You have also issued the redistribute command on RouterC to redistribute the OSPF routes from RouterA into BGP.
Routes to which of the following networks will RouterC advertise to RouterF? (Select the best answer.)

A. only network C
B. only networks B, C, and D
C. only networks A, B, C, and D
D. only networks A, B, C, D, and E
E. networks A, B, C, D, E, and F
Correct Answer:
D. only networks A, B, C, D, and E
Answer Description:
RouterC will advertise only networks A, B, C, D, and E to RouterF. RouterC and RouterF are external Border Gateway Protocol (eBGP) peers, which are BGP routers that belong to different autonomous systems (ASes). An eBGP peer advertises the following routes to another eBGP peer:

  • Routes learned through internal BGP (iBGP)
  • Routes learned through eBGP
  • Routes learned through redistribution
  • Routes originated by a network statement

The only route that RouterC will not advertise to RouterF is network F, because RouterC originally learned of the route from RouterF. When RouterF advertises network F to RouterC, RouterF adds the AS number (ASN) to the AS_PATH. Routes with an AS_PATH that contains the ASN of a BGP peer are not advertised back to that peer.

If RouterF were in AS 100, RouterF and RouterC would be iBGP peers. The BGP split horizon rule states that routes learned through iBGP are not advertised to iBGP peers. Therefore, an iBGP peer advertises the following routes to another iBGP peer:

  • Routes learned through eBGP
  • Routes learned through redistribution
  • Routes originated by a network statement

Because iBGP routes are not advertised to iBGP peers, one of the following actions must be taken to enable routers running iBGP to communicate:

  • Configure a full mesh.
  • Configure a confederation.
  • Configure a route reflector.

A full mesh configuration enables each router to learn each iBGP route independently without passing through a neighbor. However, a full mesh configuration requires the most administrative effort to configure. A confederation enables an AS to be divided into discrete units, each of which acts like a separate AS. Within each confederation, the routers must be fully meshed unless a route reflector is established. A route reflector can be used to pass iBGP routes between iBGP routers, eliminating the need for a full mesh configuration. However, it is important to note that route reflectors advertise best paths only to route reflector clients. Additionally, if multiple paths exist, a route reflector will always advertise the exit point that is closest to the route reflector.

Exam Question 212

You are connecting host computers to a switch with 10/100/1000Mbps Gigabit Ethernet ports. All of the ports are configured to autonegotiate speed and duplex settings.
Which of the following will cause a mismatch condition? (Select the best answer.)

A. connecting a NIC that is configured for halfduplex, 100Mbps operation
B. connecting a NIC that is configured for fullduplex, 100Mbps operation
C. connecting a NIC that is configured for fullduplex, 1000Mbps operation
D. connecting a NIC that is configured to autonegotiate duplex and speed settings
Correct Answer:
B. connecting a NIC that is configured for fullduplex, 100Mbps operation
Answer Description:
Connecting a network interface card (NIC) that is configured for fullduplex, 100Mbps operation will cause a mismatch condition because the duplex modes on the NIC and on the port will be different. A NIC that has been manually configured to use fullduplex or halfduplex mode does not respond to a port that is attempting to autonegotiate duplex settings. When the autonegotiating port receives no reply, it will use the default duplex settings for that speed. If the port detects that it should transmit at 10 Mbps or 100 Mbps, the port will default to halfduplex mode? if the port detects that it should transmit at 1000 Mbps, the port will default to fullduplex mode.

You can detect a duplex mismatch by monitoring a switch for %CDP-4-DUPLEXMISMATCH error messages. Additionally, you can issue the show interfacesinterface command, which displays counter information. If you see an abnormal increase in frame check sequence (FCS) errors and alignment errors on a halfduplex port, you should suspect a duplex mismatch. An abnormal increase in FCS errors and runts on a fullduplex port is also an indicator of a duplex mismatch.

Connecting a NIC that is configured for halfduplex, 100Mbps operation will not cause a mismatch condition. The port will detect that it should transmit at 100 Mbps; therefore, it will default to halfduplex mode.

Configuring both switch ports for halfduplex mode would enable only one port to send data at a time; however, communication could still occur, albeit slowly.

Connecting a NIC that is configured for fullduplex, 1000Mbps operation will not cause a mismatch condition. The port will detect that it should transmit at 1000 Mbps; therefore, it will default to fullduplex mode.

Connecting a NIC that is configured to autonegotiate duplex and speed settings will not cause a mismatch condition. When both sides of a link autonegotiate speed settings, they will select the highest speed common to both of them. When both sides of a link autonegotiate duplex settings, they will negotiate fullduplex mode if both ports support fullduplex operation. If either side of the link does not support fullduplex operation, the ports will negotiate halfduplex mode.

Exam Question 213

Which of the following CHAP packets contains a Code field that is set to a value of 4? (Select the best answer.)

A. Challenge
B. Failure
C. Response
D. Success
Correct Answer:
B. Failure
Answer Description:
A Challenge Handshake Authentication Protocol (CHAP) Failure packet contains a Code field that is set to a value of 4. A CHAP packet consists of the following fields:

  • A oneoctet Code field
  • A oneoctet Identifier field, which helps to match challenges to responses
  • A twooctet Length field,which indicates the length of the packet
  • One or more fields that are determined by the Code field

A Challenge packet has a Code field that is set to a value of 1. It also has the following additional fields:

  • A oneoctet ValueSize field, which indicates the length of the Value field
  • A variablelength ChallengeValue field, which contains a variable, unique stream of octets
  • A variablelength Name field, which identifies the name of the transmitting device

A Response packet has a Code field that is set to a value of 2. It also has the following additional fields:

  • A oneoctet ValueSize field, which indicates the length of the Response Value field
  • A variablelength Response Value field, which contains a concatenated oneway hash of the ID, the secret key, and the Challenge Value
  • A variablelength Name field, which identifies the name of the transmitting device

A Success packet has a Code field that is set to a value of 3. In addition to the standard fields, the Success packet and the Failure packet have a variablelength Message field, which displays a success or failure message, typically in humanreadable ASCII characters.

Exam Question 214

You administer the network shown in the exhibit above. You enable root guard by issuing the spanning-tree guard root command in interface configuration mode for the Fa0/0 interfaces of S2 and S3.

You administer the network shown in the exhibit above. You enable root guard by issuing the spanning-tree guard root command in interface configuration mode for the Fa0/0 interfaces of S2 and S3.

Which of the following statements best describes what will occur if the link between S1 and S2 is broken? (Select the best answer.)

A. Traffic will follow its normal path from Host2 to S1.
B. The Fa0/0 port on both switches will be put into the root-inconsistent state.
C. Only Fa0/0 on S2 will be put into the root-inconsistent state.
D. Only Fa0/0 on S3 will be put into the root-inconsistent state.
E. STP will be disabled.
Correct Answer:
C. Only Fa0/0 on S2 will be put into the root-inconsistent state.
Answer Description:
If the link between S1 and S2 is broken, the Fa0/0 port on S2 will be placed into the root-inconsistent state. Root guard is typically used to prevent a designated port from becoming a root port, thereby influencing which bridge will become the root bridge on the network. When root guard is applied to a port, the port is permanently configured as a designated port. Normally, a port that receives a superior bridge protocol data unit (BPDU) will become the root port. However, if a port configured with root guard receives a superior BPDU, the port transitions to the rootinconsistent state and no data will flow through that port until it stops receiving superior BPDUs. As a result, root guard can be used to influence the placement of the root bridge on a network by preventing other switches from propagating superior BPDUs throughout the network and becoming the root bridge.

When the root bridge detects the broken link, it will send out BPDUs to reconverge the network topology. Since root guard was enabled on Fa0/0 on S2, the interface will be placed into the rootinconsistent state when it receives superior BPDUs from Fa0/0 on S3. Thus root guard prevents Fa0/0 on S2 from being selected as a root port. The port will remain in the rootinconsistent state until it stops receiving superior BPDUs from Fa0/0 on S3.
Fa0/0 on S3 will not be placed into the rootinconsistent state, because it will not receive superior BPDUs
from S2. S3 will continue to receive superior BPDUs from S1.

Traffic would not follow its normal path from Host2 to the root bridge if the link between S1 and S2 were broken. When the link between S1 and S2 is up, traffic from Host2 travels from S4 to S2 to S1. This is based on the root path cost. The root path cost is an accumulation of path costs from bridge to bridge. A Fast Ethernet link has a path cost of 19. There are two 100Mbps paths, so the root path cost from S4 to S2 to S1 equals 38. The root path cost from S4 to S3 to S1 also equals 38. If the root path cost is identical, the bridge ID is used to determine the path. In this scenario, S2 has a priority of 32768, as does S3. However, the Media Access Control (MAC) address for S2, 000000000002, is lower than the MAC address for S3, 000000000003, making S2 the designated bridge. If the link between S1 and S2 breaks, the path for traffic coming from Host2 will be rerouted from its normal path to the S4 to S3 to S1 path. Spanning Tree Protocol (STP) would not be disabled if the link between S1 and S2 were to break. It is STP that reconverges the network topology to reroute traffic after a link in the root path becomes disabled.

Exam Question 215

Which of the following statements is true regarding Cisco IOS EPC? (Select the best answer.)

A. Each capture point can be associated with multiple capture buffers.
B. Multiple capture points can be active on a single interface.
C. The buffer type and sampling interval are the only settings you can adjust when creating a capture buffer.
D. The packet data contains a timestamp indicating when the packet was added to the buffer.
Correct Answer:
B. Multiple capture points can be active on a single interface.
Answer Description:
Multiple capture points can be active on a single interface. Cisco IOS Embedded Packet Capture (EPC) is a feature that you can implement to assist with tracing packets and troubleshooting issues with packet flow in and out of Cisco devices. To implement Cisco IOS EPC, you must perform the following steps:

  1. Create a capture buffer.
  2. Create a capture point.
  3. Associate the capture point with the capture buffer.
  4. Enable the capture point.

The buffer type and sampling interval are not the only settings you can adjust when creating a capture buffer; you can also adjust several other items, including the buffer size and the packet capture rate. Specifying the sampling interval and the buffer type will allow for the maximum number of pertinent packets to be stored in the buffer. To configure a capture buffer, you should issue the monitor capture bufferbuffername [clear | exportexportlocation | filteraccesslistipaccesslist | limit {allownthpaknthpacket | duration seconds | packetcounttotalpackets | packetspersec packets} | [maxsize elementsize] [sizebuffersize] [circular | linear]] command from global configuration mode.

The capture buffer contains packet data and metadata. The packet data does not contain a timestamp indicating when the packet was added to the buffer; the timestamp is contained within the metadata. In addition, the metadata contains information regarding the direction of transmission of the packet, the switch path, and the encapsulation type.

To create a capture point, you should issue the monitor capture point {ip | ipv6} {cefcapturepointname interfacename interfacetype {both | in | out} | processswitched capturepointname {both | fromus | in | out}} command from global configuration mode. You can create multiple capture points with unique names and parameters on a single interface.

To associate a capture point with a capture buffer, you should issue the monitor capture point associatecapturepointname capturebuffername command from global configuration mode. Each capture point can be associated with only one capture buffer. Finally, to enable the capture point so that it can begin to capture packet data, you should issue the monitor capture point start {capturepointname | all} command.

Exam Question 216

Which of the following potential BGP enhancements were documented in the BGP Add-Paths proposal? (Select the best answer.)

A. possible modifications to the best-path algorithm
B. possible software upgrades for PE routers
C. possible addition of a session between a route reflector and its client
D. possible addition of a four-octet Path Identifier
Correct Answer:
D. possible addition of a four-octet Path Identifier
Answer Description:
The BGP Add-Paths proposal proposed the possible addition of a four-octet Path Identifier to Network Layer Reachability Information (NLRI) in order to enable Border Gateway Protocol (BGP) to distribute multiple paths. BGP as it is typically deployed has no mechanism for distributing paths that are not considered the best path between speakers.

Observations about the possible addition of a session between a router reflector and its client were documented in Request for Comments (RFC) 6774, which discusses the distribution of diverse BGP paths. Specifically, RFC 6774 observed that BGP as it is typically deployed has no mechanism for distributing paths that are not considered the best path between speakers. However, the possible addition of a session between a route reflector and its client could enable a BGP router to distribute alternate paths.

Neither the AddPaths proposal nor RFC 6774 document possible modifications to the bestpath algorithm or software upgrades for provider edge (PE) routers. Although RFC 6774 does discuss a possible means of distributing paths other than the best path, the means by which BGP determines the best path to a destination were not changed. Therefore, no software upgrade is required.

Exam Question 217

Which of the following is true regarding RTC? (Select the best answer.)

A. RTC sends only the prefixes that the PE router wants.
B. RTC finds route inconsistencies.
C. RTC synchronizes peers without a hard reset.
D. RTC works with only VPNv4.
E. RTC makes the ABR an RR and sets the next hop to self.
Correct Answer:
A. RTC sends only the prefixes that the PE router wants.
Answer Description:
Route Target Constraint (RTC) sends only the prefixes that the Provider Edge (PE) router wants. In a normal Multiprotocol Label Switching (MPLS) virtual private network (VPN), the route reflector (RR) sends all of its VPN version 4 (VPNv4) and VPNv6 prefixes to the PE router. The PE router then drops the prefixes for which it does not have a matching VPN routing and forwarding (VRF). RTC allows a PE router to send its route target (RT) membership data to the RR within an address family named rtfilter. The RR then uses rtfilter to determine which prefixes to send to the PE. In order for RTC to work, both the RR and the PE need to support RTC.

RTC does not find route inconsistencies, nor does it synchronize peers without a hard reset. This functionality is provided by Border Gateway Protocol (BGP) Enhanced Route Refresh. BG Enhanced Route Refresh is enabled by default. If two BGP peers support EnhancedRoute Refresh, each peer will send a RouteRefresh StartofRIB (SOR) message and a RouteRefresh EndofRIB (EOR) message before and after an AdjRIBOut message, respectively. After a peer receives an EOR message, or after the EOR timer expires, the peer will check to see whether it has any routes that were not readvertised.

If any stale routes remain, they are deleted and the route inconsistency is logged. RTC does not make the area border router (ABR) an RR, nor does it set the next hop to self. This behavior is exhibited by Unified MPLS. Unified MPLS increases scalability for an MPLS network by extending the label switched path (LSP) from end to end, not by redistributing interior gateway protocols (IGPs) into one another, but by distributing some of the IGP prefixes into BGP. BGP then distributes those prefixes throughout the network.

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