[2021-New] Cisco 400-101 Dumps With Update Exam Questions (261-270)

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Q1. What is the maximum number of classes that MQC can support in a single policy map?

A. 512

B. 256

C. 128

D. 64

Answer: B

Q2. Which two events occur when a packet is decapsulated in a GRE tunnel? (Choose two.)

A. The destination IPv4 address in the IPv4 payload is used to forward the packet.

B. The TTL of the payload packet is decremented.

C. The source IPv4 address in the IPv4 payload is used to forward the packet.

D. The TTL of the payload packet is incremented.

E. The version field in the GRE header is incremented.

F. The GRE keepalive mechanism is reset.

Answer: A,B

Explanation:

After the GRE encapsulated packet reaches the remote tunnel endpoint router, the GRE packet is decapsulated. The destination address lookup of the outer IP header (this is the same as the tunnel destination address) will find a local address (receive) entry on the ingress line card. The first step in GRE decapsulation is to qualify the tunnel endpoint, before admitting the GRE packet into the router, based on the combination of tunnel source (the same as source IP address of outer IP header) and tunnel destination (the same as destination IP address of outer IP header). If the received packet fails tunnel admittance qualification check, the packet is dropped by the decapsulation router. On successful tunnel admittance check, the decapsulation strips the outer IP and GRE header off the packet, then starts processing the inner payload packet as a regular packet. When a tunnel endpoint decapsulates a GRE packet, which has an IPv4/IPv6 packet as the payload, the destination address in the IPv4/IPv6 payload packet header is used to forward the packet, and the TTL of the payload packet is decremented.

Reference: http://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k_r5-3/addr-serv/configuration/guide/b-ipaddr-cg53asr9k/b-ipaddr-cg53asr9k_chapter_01001.html

Q3. Which statement is true about Fast Link Pulses in Ethernet?

A. They are used during collision detection.

B. They are used only if the media type is optical.

C. They are part of UniDirectional Link Detection.

D. They are used during autonegotiation.

Answer: D

Explanation:

To make sure that your connection is operating properly, IEEE 802.3 Ethernet employs normal link pulses (NLPs), which are used for verifying link integrity in a 10BaseT system. This signaling gives you the link indication when you attach to the hub and is performed between two directly connected link interfaces (hub-to-station or station-to-station). NLPs are helpful in determining that a link has been established between devices, but they are not a good indicator that your cabling is free of problems. An extension of NLPs is fast link pulses. These do not perform link tests, but instead are employed in the autonegotiation process to advertise a device's capabilities.

Reference:

http://www.cisco.com/en/US/docs/internetworking/troubleshooting/guide/tr1904.html

Q4. In which way does the Bridge Assurance mechanism modify the default spanning-tree behavior in an effort to prevent bridging loops?

A. Received BPDUs are looped back toward the sender to ensure that the link is bidirectional.

B. If BPDUs are no longer received on a port, the switch immediately sends out a TCN BPDU.

C. Extended topology information is encoded into all BPDUs.

D. BPDUs are sent bidirectional on all active network ports, including blocked and alternate ports.

Answer: D

Q5. Which Cisco IOS VPN technology leverages IPsec, mGRE, dynamic routing protocol, NHRP, and

Cisco Express Forwarding?

A. FlexVPN

B. DMVPN

C. GETVPN

D. Cisco Easy VPN

Answer: B

Q6. Which command drops packets with unknown source addresses until you remove a sufficient number of secure MAC addresses to drop below the maximum value, and also causes the Security Violation counter to increment?

A. switchport port-security violation protect

B. switchport port-security violation drop

C. switchport port-security violation shutdown

D. switchport port-security violation restrict

Answer: D

Explanation:

When configuring port security violation modes, note the following information:

. protect—Drops packets with unknown source addresses until you remove a sufficient number of secure MAC addresses to drop below the maximum value.

. restrict—Drops packets with unknown source addresses until you remove a sufficient number of secure MAC addresses to drop below the maximum value and causes the SecurityViolation counter to increment.

. shutdown—Puts the interface into the error-disabled state immediately and sends an SNMP trap notification.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/port_sec.html

Q7. Which three message types are used for prefix delegation in DHCPv6? (Choose three.)

A. DHCP Discover

B. Renew

C. Solicit

D. DHCP Offer

E. Advertise

F. DHCP Ack

Answer: B,C,E

Explanation:

DHCPv6 Message Types

For a client to get an IPv6 address successfully from a DHCPv6 server, the Client-Server Conversation happens using the following messages.

Client--->Server Messages

Server--->Client Messages

Solicit, Request, Confirm, Renew, Rebind, Release, Decline, Information-Request Advertise, Reply, Reconfigure

Lets look at each message types in detail:

SOLICIT

This is the first step in DHCPv6, where a DHCPv6 client sends a Solicit message to locate DHCPv6 servers.

ADVERTISE

Upon receiving a Solicit Message from the client, the DHCPv6 server sends an Advertise message to indicate that it is available for DHCP service, in response to a Solicit message received from a client.

REQUEST

This message is sent by the DHCPv6 client.Client sends a Request message to request configuration parameters which includes IP addresses or delegated prefixes, from a specific server.

CONFIRM

Confirm message is sent by the client to any available server in the network to confirm that the client is still on the same link or it has to be removed. This message also confirms the IPv6 addresses that are assigned to the link are still valid. This could happen in case when a client detects a change in link-layer connectivity or if the device is powered on and it is found that one or more leases are still valid. Note that only the prefix portion of the addresses are validated and not the actual leases.

RENEW

A client sends a Renew message to the server when it wants to extend the lifetimes on the addresses and other configuration parameters assigned to the client and also to update other configuration parameters.

REBIND

In case of No response from the DHCPv6 Server for the Renew message, the client sends a Rebind message to any available server to extend the lifetimes on the address and to update other configuration parameters.

A Reply message is sent by the DHCPv6 Server in response to a Solicit, Request, Renew, Rebind message received from a client. The reply message is sent by the server in response to a confirm message (either confirming or denying) that the addresses assigned to the client are appropriate.In short the server acknowledge receipt of a Release or Decline message by sending a REPLY message.

RELEASE

Release message as the name implies, is sent by the client to the server that has assigned the addresses, to indicate that the client will no longer use the assigned addresses (one or more).

DECLINE

Client sends a Decline message to the DHCPv6 server to tell that the one or more addresses assigned by the server is already in use

RECONFIGURE

The Reconfigure Message is sent by the DHCPv6 server to the client when the server has new or updated information of configuration parameters. It tells the client to initiate a information-request/reply message to the server so as to receive the updated information.

INFORMATION-REQUEST

Information-Request message is sent by the client to the server to update the configuration parameters

Reference: https://supportforums.cisco.com/blog/153426/implementing-dhcpv6-introduction

Q8. DRAG DROP

Drag and Drop Cisco PFR adjacency types.

Answer:

Q9. Which two statements about BGP best-path selection are true? (Choose two.)

A. The route with the highest local preference is preferred.

B. The weight attribute is advertised to peers.

C. The route with the lowest MED is preferred.

D. A route that originates from iBGP peers is preferred.

E. A route that originates from a router with a higher BGP router ID is preferred.

F. The lowest weight advertised is preferred.

Answer: A,C

Q10. In the DiffServ model, which class represents the lowest priority with the lowest drop probability?

A. AF11

B. AF13

C. AF41

D. AF43

Answer: A

Explanation:

Assured Forwarding (AF) Behavior Group

Class 1

Class 2

Class 3

Class 4

Low Drop

AF11 (DSCP 10)

AF21 (DSCP 18)

AF31 (DSCP 26)

AF41 (DSCP 34)

Med Drop

AF12 (DSCP 12)

AF22 (DSCP 20)

AF32 (DSCP 28)

AF42 (DSCP 36)

High Drop

AF13 (DSCP 14)

AF23 (DSCP 22)

AF33 (DSCP 30)

AF43 (DSCP 38)

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