Exam Code: cisco 400 101 (Practice Exam Latest Test Questions VCE PDF)
Exam Name: CCIE Routing and Switching (v5.0)
Certification Provider: Cisco
Free Today! Guaranteed Training- Pass passleader 400 101 Exam.
♥♥ 2021 NEW RECOMMEND ♥♥
Free VCE & PDF File for Cisco 400-101 Real Exam (Full Version!)
★ Pass on Your First TRY ★ 100% Money Back Guarantee ★ Realistic Practice Exam Questions
Free Instant Download NEW 400-101 Exam Dumps (PDF & VCE):
Available on:
http://www.surepassexam.com/400-101-exam-dumps.html
Q61. Refer to the exhibit.
Why is R2 unable to ping the loopback interface of R4?
A. The local preference is too high.
B. The weight is too low.
C. The next hop is not reachable from R2.
D. The route originated from within the same AS.
Answer: C
Explanation:
Before a BGP speaker installs a route to a network in the main IP routing table, the router must know how to reach the next hop that is used to get to that network. Route reachability is verified by searching for a route to the next hop in the main IP routing table. Unlike IGP routing protocols, such as EIGRP and OSPF, which assume that a route is reachable if they learned it through a valid adjacency, BGP does not install routes that it cannot verify as reachable. If a route to the next hop for a BGP network is found in the main IP routing table, BGP assumes that the network is reachable, and that the particular BGP route might be stored in the main IP routing table. If the router receives a route to a network that is not reachable, that route continues to be stored in the incoming BGP table, adj-RIB-In, and might be seen using the show ip bgp command, but is not placed in the main IP routing table.
Reference: https://www.informit.com/library/content.aspx?b=CCIE_Practical_Studies_II&seqNum=75
Q62. DRAG DROP
Drag and drop the IPv6 multicast feature on the left to its corresponding function on the right.
Answer:
Q63. Which Carrier Ethernet service supports the multiplexing of multiple point-to-point EVCs across as a single UNI?
A. EPL
B. EVPL
C. EMS
D. ERMS
Answer: B
Explanation:
Ethernet Relay Service (ERS or EVPL)
An Ethernet Virtual Circuit (EVC) is used to logically connect endpoints, but multiple EVCs
could exist per single UNI. Each EVC is distinguished by 802.1q VLAN tag identification.
The ERS network acts as if the Ethernet frames have crossed a switched network, and certain control traffic is not carried between ends of the EVC. ERS is analogous to Frame Relay where the CE-VLAN tag plays the role of a Data-Link Connection Identifier (DLCI). The MEF term for this service is EVPL.
Reference: http://www.cisco.com/c/en/us/td/docs/net_mgmt/ip_solution_center/5-1/carrier_ethernet/user/guide/l2vpn51book/concepts.html
Q64. Which statement about a P router in a Layer 3 MPLS VPN is true?
A. It is unaware of VPN routes.
B. It connects to customer edge routers.
C. It participates in MPLS VPN routing.
D. It uses the running IGP to share VPN routes.
Answer: A
Q65. When you configure the ip pmtu command under an L2TPv3 pseudowire class, which two things can happen when a packet exceeds the L2TP path MTU? (Choose two.)
A. The router drops the packet.
B. The router always fragments the packet after L2TP/IP encapsulation.
C. The router drops the packet and sends an ICMP unreachable message back to the sender only if the DF bit is set to 1.
D. The router always fragments the packet before L2TP/IP encapsulation.
E. The router fragments the packet after L2TP/IP encapsulation only if the DF bit is set to 0.
F. The router fragments the packet before L2TP/IP encapsulation only if the DF bit is set to
0.
Answer: C,F
Explanation:
If you enable the ip pmtu command in the pseudowire class, the L2TPv3 control channel participates in the path MTU discovery. When you enable this feature, the following processing is performed:
– ICMP unreachable messages sent back to the L2TPv3 router are deciphered and the tunnel MTU is updated accordingly. In order to receive ICMP unreachable messages for fragmentation errors, the DF bit in the tunnel header is set according to the DF bit value received from the CE, or statically if the ip dfbit set option is enabled. The tunnel MTU is periodically reset to the default value based on a periodic timer.
– ICMP unreachable messages are sent back to the clients on the CE side. ICMP unreachable messages are sent to the CE whenever IP packets arrive on the CE-PE interface and have a packet size greater than the tunnel MTU. A Layer 2 header calculationis performed before the ICMP unreachable message is sent to the CE.
Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_0s/feature/guide/l2tpv325.html
Q66. Two routers are trying to establish an OSPFv3 adjacency over an Ethernet link, but the adjacency is not forming. Which two options are possible reasons that prevent OSPFv3 to form between these two routers? (Choose two.)
A. mismatch of subnet masks
B. mismatch of network types
C. mismatch of authentication types
D. mismatch of instance IDs
E. mismatch of area types
Answer: D,E
Explanation:
An OSPFv3 interface must have a compatible configuration with a remote interface before the two can be considered neighbors. The two OSPFv3 interfaces must match the following criteria:
. Hello interval
. Dead interval
. Area ID
. Optional capabilities
The OSPFv3 header includes an instance ID field to identify that OSPFv3 packet for a particular OSPFv3 instance. You can assign the OSPFv3 instance. The interface drops all OSPFv3 packets that do not have a matching OSPFv3 instance ID in the packet header.
Reference: http://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/unicast/configuration/guide/l3_cli_nxos/l3_ospfv3.html
Q67. 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
Q68. 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.
Answer: D
Explanation:
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 preferred path fails.
. 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
Q69. Which BGP feature allows BGP routing tables to be refreshed without impacting established BGP sessions?
A. BGP synchronization
B. soft reconfiguration
C. confederations
D. hard reset
Answer: B
Explanation:
Clearing a BGP session using a hard reset invalidates the cache and results in a negative impact on the operation of networks as the information in the cache becomes unavailable. Soft reset is recommended because it allows routing tables to be reconfigured and activated without clearing the BGP session. Soft reset is done on a per-neighbor basis.
Reference: http://www.cisco.com/en/US/products/ps6599/products_data_sheet09186a0080087b3a.ht ml
Q70. Refer to the exhibit.
Switch DSW1 should share the same MST region with switch DSW2. Which statement is true?
A. Configure DSW1 with the same version number, and VLAN-to-instance mapping as shown on DSW2.
B. Configure DSW1 with the same region name, number, and VLAN-to-instance mapping as shown on DSW2.
C. DSW2 uses the VTP server mode to automatically propagate the MST configuration to DSW1.
D. DSW1 is in VTP client mode with a lower configuration revision number, therefore, it automatically inherits MST configuration from DSW2.
E. DSW1 automatically inherits MST configuration from DSW2 because they have the same domain name.
Answer: B
