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2021 Jan ccie 400 101:
Q481. 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
Q482. DRAG DROP
Drag and Drop Cisco PFR adjacency types.
Answer:
Q483. In the DiffServ model, which class represents the highest priority with the highest drop probability?
A. AF11
B. AF13
C. AF41
D. AF43
Answer: D
Explanation:
AF43 — Assured forwarding, high drop probability, Class 4 DSCP, and Flash-override precedence.
Table of AF Classes and Drop Priority
Drop Precedence
Class 1
Class 2
Class 3
Class 4
Low drop
AF11
DSCP 10
001010
AF21
DSCP 18
010010
AF31
DSCP 26
011010
AF41
DSCP 34
100010
Medium drop
AF12
DSCP 12
001100
AF22
DSCP 20
010100
AF32
DSCP 28
011100
AF42
DSCP 36
100100
High drop
AF13
DSCP 14
001110
AF23
DSCP 22
010110
AF33
DSCP 30
011110
AF43
DSCP 38
100110
Reference:
https://www.informit.com/library/content.aspx?b=CCIE_Practical_Studies_II&seqNum=56
Q484. Refer to the exhibit.
Why is the router out of memory?
A. The router is experiencing a BGP memory leak software defect.
B. The BGP peers have been up for too long.
C. The amount of BGP update traffic in the network is too high.
D. The router has insufficient memory due to the size of the BGP database.
Answer: D
Explanation:
Here we can see that this router is running out of memory due to the large size of the BGP routing database. In this case, this router is receiving over 200,000 routes from each of the 4 peers.
Q485. 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.
Answer: D
Explanation:
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
Renewal ccie pdf download:
Q486. Which option describes how a VTPv3 device responds when it detects a VTPv2 device on a trunk port?
A. It sends VTPv3 packets only.
B. It sends VTPv2 packets only.
C. It sends VTPv3 and VTPv2 packets.
D. It sends a special packet that contains VTPv3 and VTPv2 packet information.
Answer: C
Explanation:
When a VTP version 3 device on a trunk port receives messages from a VTP version 2 device, the VTP version 3 device sends a scaled-down version of the VLAN database on that particular trunk in a VTP version 2 format. A VTP version 3 device does not send out VTP version 2-formatted packets on a trunk port unless it first receives VTP version 2 packets on that trunk. If the VTP version 3 device does not receive VTP version 2 packets for an interval of time on the trunk port, the VTP version 3 device stops transmitting VTP version 2 packets on that trunk port. Even when a VTP version 3 device detects a VTP version 2 device on a trunk port, the VTP version 3 device continues to send VTP version 3 packets in addition to VTP version 3 device 2 packets, to allow two kinds of neighbors to coexist on the trunk. VTP version 3 sends VTP version 3 and VTP version 2 updates on VTP version 2-detected trunks.
Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/vtp.html
Q487. Which two statements about IOS and IOS XE are true? (Choose two.)
A. IOS XE can upgrade and restart applications independently of IOS.
B. Only IOS uses the FFM to provide separation between the control plane and the data plane.
C. IOS XE provides improved functionality and an enhanced UI.
D. Only IOS runs as a single daemon within the Linux OS.
E. IOS XE provides additional system functions that run as multiple separate processes in the OS.
Answer: A,E
Q488. Which three benefits does the Cisco Easy Virtual Network provide to an enterprise network?
(Choose three.)
A. simplified Layer 3 network virtualization
B. improved shared services support
C. enhanced management, troubleshooting, and usability
D. reduced configuration and deployment time for dot1q trunking
E. increased network performance and throughput
F. decreased BGP neighbor configurations
Answer: A,B,C
Q489. Which two options are the two main phases of PPPoE? (Choose two.)
A. Active Discovery Phase
B. IKE Phase
C. Main Mode Phase
D. PPP Session Phase
E. Aggressive Mode Phase
F. Negotiation Phase
Answer: A,D
Explanation:
PPPoE is composed of two main phases:
Active Discovery Phase — In this phase, the PPPoE client locates a PPPoE server, called an access concentrator. During this phase, a Session ID is assigned and the PPPoE layer is established.
PPP Session Phase — In this phase, PPP options are negotiated and authentication is performed. Once the link setup is completed, PPPoE functions as a Layer 2 encapsulation method, allowing data to be transferred over the PPP link within PPPoE headers.
Reference: http://www.cisco.com/c/en/us/td/docs/security/asa/asa92/configuration/vpn/asa-vpn-cli/vpn-pppoe.html
Q490. Which two BGP path attributes are visible in Wireshark? (Choose two.)
A. weight
B. AS path
C. local preference
D. route maps
Answer: B,C