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Q451. DRAG DROP
Drag and drop the fragmentation characteristics on the left to the corresponding protocol on the right.
Answer:
Q452. Which two statements about the command distance bgp 90 60 120 are true? (Choose two.)
A. Implementing the command is a Cisco best practice.
B. The external distance it sets is preferred over the internal distance.
C. The internal distance it sets is preferred over the external distance.
D. The local distance it sets may conflict with the EIGRP administrative distance.
E. The internal distance it sets may conflict with the EIGRP administrative distance.
F. The local distance it sets may conflict with the RIP administrative distance.
Answer: C,F
Explanation:
To allow the use of external, internal, and local administrative distances that could be a better route than other external, internal, or local routes to a node, use the distance bgp command in address family or router configuration mode. To return to the default values, use the no form of this command. distance bgp external-distance internal-distance local-distance no distance bgp
. Syntax Description
external-distance
Administrative distance for BGP external routes. External routes are routes for which the best path is learned from a neighbor external to the autonomous system. Accept table values are from 1 to 255. The default is 20. Routes with a distance of 255 are not installed in the routing table.
internal-distance
Administrative distance for BGP internal routes. Internal routes are those routes that are learned from another BGP entity within the same autonomous system. Accept table values are from 1 to 255. The default is 200. Routes with a distance of 255 are not installed in the routing table.
local-distance
Administrative distance for BGP local routes. Local routes are those networks listed with a network router configuration command, often as back doors, for that router or for networks that are being redistributed from another process. Accept table values are from 1 to 255. The default is 200. Routes with a distance of 255 are not installed in the routing table.
Defaults
external-distance: 20
internal-distance: 200
local-distance: 200
In this case, the internal distance is 60 and the external is 90, and the local distance is 120 (same as RIP).
Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_2/iproute/command/reference/fiprrp_r/1rfbgp1. html#wp1113874
Q453. What is the hop limit for an MLD message?
A. 1
B. 2
C. 15
D. 255
Answer: A
Explanation:
MLD uses the Internet Control Message Protocol (ICMP) to carry its messages. All MLD messages are link-local with a hop limit of 1, and they all have the alert option set. The alert option implies an implementation of the hop-by-hop option header.
Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_lsm/configuration/xe-3s/imc-lsm-xe-3s-book/ipv6-mcast-mld-xe.html
Q454. Which statement about UDLD is true?
A. The udld reset command resets ports that have been error-disabled by both UDLD and Fast UDLD.
B. Fast UDLD is configured in aggressive mode.
C. Only bidirectional link failures can be detected in normal mode.
D. Each switch in a UDLD topology can send and receive packets to and from its neighbors.
Answer: A
Q455. Which EEM event detector is triggered by hardware installation or removal?
A. Enhanced-Object-Tracking Event Detector
B. Resource Event Detector
C. OIR Event Detector
D. CLI Event Detector
Answer: C
Q456. What is a reason for 6PE to use two MPLS labels in the data plane instead of one?
A. 6PE allows penultimate hop popping and has a requirement that all P routers do not have to be IPv6 aware.
B. 6PE does not allow penultimate hop popping.
C. It allows MPLS traffic engineering to work in a 6PE network.
D. It allows 6PE to work in an MPLS network where 6VPE is also deployed.
Answer: A
Explanation:
Q. Why does 6PE use two MPLS labels in the data plane?
A. 6PE uses two labels:
. The top label is the transport label, which is assigned hop-by-hop by the Label Distribution Protocol (LDP) or by MPLS traffic engineering (TE).
. The bottom label is the label assigned by the Border Gateway Protocol (BGP) and advertised by the internal BGP (iBGP) between the Provider Edge (PE) routers.
When the 6PE was released, a main requirement was that none of the MPLS core routers (the P routers) had to be IPv6-aware. That requirement drove the need for two labels in the data plane. There are two reasons why the 6PE needs both labels.
PHP Functionality
If only the transport label were used, and if penultimate hop popping (PHP) were used, the penultimate hop router (the P router) would need to understand IPv6.
With PHP, this penultimate hop router would need to remove the MPLS label and forward the packet as an IPv6 packet. This P router would need to know that the packet is IPv6 because the P router would need to use the correct Layer 2 encapsulation type for IPv6. (The encapsulation type is different for IPv6 and IPv4; for example, for Ethernet, the encapsulation type is 0x86DD for IPv6, while it is 0x0800 for IPv4.) If the penultimate hop router is not IPv6-capable, it would likely put the Layer 2 encapsulation type for IPv4 for the IPv6 packet. The egress PE router would then believe that the packet was IPv4. There is time-to-live (TTL) processing in both the IPv4 and IPv6 headers. In IPv6, the field is called Hop Limit. The IPv4 and IPv6 fields are at different locations in the headers. Also, the Header Checksum in the IPv4 header would also need to be changed; there is no Header Checksum field in IPv6. If the penultimate hop router is not IPv6-capable, it would cause the IPv6 packet to be malformed since the router expects to find the TTL field and Header Checksum field in the header. Because of these differences, the penultimate hop router would need to know it is an IPv6 packet. How would this router know that the packet is an IPv6 packet, since it did not assign a label to the IPv6 Forwarding Equivalence Class (FEC), and there is no encapsulation field in the MPLS header? It could scan for the first nibble after the label stack and determine that the packet is IPv6 if the value is 6. However, that implies that the penultimate hop router needs to be IPv6-capable. This scenario could work if the explicit null label is used (hence no PHP). However, the decision was to require PHP.
Load Balancing
Typical load balancing on a P router follows this process. The P router goes to the end of the label stack and determines if it is an IPv4 packet by looking at the first nibble after the label stack.
. If the nibble has a value of 4, the MPLS payload is an IPv4 packet, and the P router load balances by hashing the source and destination IPv4 addresses.
. If the P router is IPv6-capable and the value of the nibble is 6, the P router load balances by hashing the source and destination IPv6 addresses.
. If the P router is not IPv6-capable and the value of the nibble is not 4 (it could be 6 if the packet is an IPv6 packet), the P router determines it is not an IPv4 packet and makes the load balancing decision based on the bottom label. In the 6PE scenario, imagine there are two egress PE routers advertising one IPv6 prefix in BGP towards the ingress PE router. This IPv6 prefix would be advertised with two different labels in BGP. Hence, in the data plane, the bottom label would be either of the two labels. This would allow a P router to load balance on the bottom label on a per-flow basis. If 6PE used only the transport label to transport the 6PE packets through the MPLS core, the P routers would not be able to load balance these packets on a per-flow basis unless the P routers were IPv6-capable. If the P routers were IPv6-capable, they could use the source and destination IPv6 addresses in order to make a load balancing decision.
Reference: http://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/116061-qa-6pe-00.html
Q457. DRAG DROP
Drag and drop the BGP attribute on the left to the correct category on the right.
Answer:
Q458. Refer to the exhibit.
Which log levels are enabled for the console?
A. informational only
B. informational and debugging
C. informational, debugging, notifications, warnings, errors, critical, alerts, and emergencies
D. informational, notifications, warnings, errors, critical, alerts, and emergencies
Answer: D
Q459. Refer to the exhibit.
Which VLANs are permitted to send frames out port FastEthernet0/1?
A. 100 - 200
B. 4 - 100
C. 1 and 4 - 100
D. 3 and 4 - 100
Answer: D
Explanation:
Traffic on the native vlan does not get tagged as it crosses a trunk, so there is no dot1q tag in the first place to be filtered. And you don’t need to allow the native vlan. But if we force to tag the native vlan (with the “switchport trunk native vlan tag” command) then if the native vlan is not in the “allowed vlan” list it will be dropped.
Q460. DRAG DROP
Drag and drop each description of IPv6 transition technology on the left to the matching IPv6 transition technology category on the right.
Answer: