400-051 | What Virtual 400-051 vce Is?

Question No: 15

ln Cisco lOS routers that use low latency queuing, which algorithm is used to presort traffic going into the default queue?

A. first-in, first-out

B. last-in, first-out

C. weighted round robin

D. fair queuing

E. random processing

Answer: D

Explanation:

WFQ is a flow-based queuing algorithm used in Quality of Service (QoS) that does two things simultaneously: lt schedules interactive traffic to the front of the queue to reduce response time, and it fairly shares the remaining bandwidth between high bandwidth flows. A stream of packets within a single session of a single application is known as flow or conversation. WFQ is a flow-based method that sends packets over the network and ensures packet transmission efficiency which is critical to the interactive traffic. This method automatically stabilizes network congestion between individual packet transmission flows.

Question No: 16

Which entity signs a Cisco lP phone LSC?

A. Godaddy.com Enrollment Server

B. Manufacturer Certificate Authority

C. Registration Authority

D. Certificate Authority Proxy Function

E. Cisco Certificate Authority

Answer: D

Explanation:

By default, LSC certificates are not installed on Cisco lP phones. Cisco lP phones that are required to use LSC certificates must be provisioned to allow TLS transactions before deployment in the field. LSC certificates can be provisioned to the Cisco lP phones through the Certificate Authority Proxy Function (CAPF) process. This process is completed using TLS and USB tokens coupled with the CTL client. Moreover, the Cisco ASA Phone Proxy feature can serve LSC certificates to the Cisco lP phones. Cisco lP phones will only work with the Cisco ASA Phone Proxy and will not establish secure connectivity with the Cisco Unified Communications Manager.

Question No: 17

Which device is the initiator of a StationD message in a Cisco Unified Communications Manager SDl trace?

A. SCCP lP phone

B. SlP lP phone

C. Cisco Unified Communications Manager

D. MGCP analog gateway

E. digital voice gateway

Answer: C

Explanation:

All messages to and from a skinny device are preceded by either the words StationD or Stationlnit. StationD messages are sent from call manager to lP phone. Skinny message transmission such as this between the lP phone and CallManger occurs for every action undertaken by the lP phone, includinginitialization, registration, on-hook, off-hook, dialing of the digits, key press on the phone, and so much more.

Question No: 18

Refer to the exhibit.

How many inbound calls can be handled simultaneously between ephone 1 and ephone 2 before a user busy tone is returned?

A. 6

B. 7

C. 8

D. 9

E. 11

Answer: A

Explanation:

Because hunt stop channel is set to 6 as it enables call hunting to up to six channels of this ephone-dn and remaining 2 channels are available for outgoing call features.

Reference:

http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucme/command/reference/cme_cr/cme_e1ht.html

Question No: 19

Which message is used by a Cisco lOS MGCP gateway to send periodic keepalives to its call agent?

A. CRCX

B. AUCX

C. NTFY

D. RQNT

E. 200 OK

Answer: C

Explanation:

The gateway maintains this connection by sending empty MGCP Notify (NTFY) keepalive messages to Cisco CallManager at 15-second intervals. lf the active Cisco CallManager fails to acknowledge receipt of the keepalive message within 30 seconds, the gateway attempts to switch over to the next highest order Cisco CallManager server that is available.

lf none of the Cisco CallManager servers respond, the gateway switches into fallback mode and reverts to its default H.323 session application for basic call control support of lP telephony activity in the network.

Question No: 20

According to lTU-T E.164 recommendations, which two fields in the National Significant Number code may be further subdivided? (Choose two.)

A. Country Code

B. National Destination Code

C. Subscriber Number

D. Regional Significant Number

E. Local User Code

F. National Numbering Plan

Answer: B, C

Explanation:

A telephone number can have a maximum of 15 digits .The first part of the telephone number is the country code (one to three digits) .The second part is the national destination code (NDC). The last part is the subscriber number (SN). The NDC and SN together are collectively called the national (significant) number.

Question No: 21

Refer to the exhibit.

Which ephone-dn can join the hunt group whenever a wild card slot becomes available?

A. ephone-dn 1

B. ephone-dn 2

C. ephone-dn 3

D. ephone-dn 4

E. ephone-dn 6

Answer: C

Explanation: Reference: http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucme/command/reference/cme_cr/cme_e1ht.html

Question No: 22

Refer to the exhibit.

Which number is sent as the caller lD when a user at extension 5001 places a call that matches this translation profile?

A. 14087775001

B. +4087775001

C. 4087750001

D. +14087775001

Answer: D

Explanation:

When someone dials 5001, it will match rule 2 because it exactly starts with 5(five) using the " sign and ends with [0-9] followed by $. ln replace pattern you can see +1408777 & means all set of match pattern. Thus, +14087775001.

Question No: 23

Which two are characteristics of jitter buffers? (Choose two.)

A. Jitter buffers are used to change asynchronous packet arrivals into a synchronous stream by turning variable network delays into constant delays at the destination end systems.

B. Jitter buffers are used to change asynchronous packet arrivals into a synchronous stream by turning variable network delays into constant delays at the sending systems.

C. The role of the jitter buffer is to balance the delay and the probability of interrupted playout due to late packets.

D. The role of the jitter buffer is to queue late packets and reorder out-of-order packets.

E. Jitter buffers are used to change asynchronous packet arrivals into a synchronous stream by queuing packets into constant delays at the sending systems.

Answer: A, C

Explanation:

Jitter buffers are used to remove the effects of jitter so that asynchronous packet arrivals are changed to a

synchronous stream. The jitter buffer trades off between delay and the probability of interrupted playout because of late packets (discard).

Reference:

http://www.appneta.com/blog/jitter-voip/

Question No: 24

What is the maximum length of any numeric geographic area address in lTU recommendation E.164?

A. 15

B. 18

C. 21

D. 22

E. 25

Answer: A

Explanation:

E.164 defines a general format for international telephone numbers. Plan-conforming numbers are limited to a maximum of 15 digits. The presentation of numbers is usually prefixed with the character + (plus sign), indicating that the number includes the international country calling code (country code), and must typically be prefixed when dialing with the appropriate international call prefix, which is a trunk code to reach an international circuit from within the country of call origination.