GateKeepers

Here you will find answers to CVoice – Gatekeeper Questions

Question 1

The SJ local zone contains a gatekeeper that controls two gateways, SJ1 and SJ2. Both gateways provide access to area code 408. Which two command strings should be entered into the gatekeeper to give the SJ2 gateway priority over the SJ1 gateway? (Choose two.)

A. zone prefix SJ 408 gw-priority 6 SJ1
B. zone prefix SJ 408 gw-priority 6 SJ2
C. zone prefix SJ 408 gw-priority 10 SJ1
D. zone prefix SJ 408 gw-priority 10 SJ2
E. zone prefix SJ 408 gw-priority 0 SJ2, 10 SJ1
F. zone prefix SJ 408 gw-priority 6 SJ1, 10 SJ2

Answer: A D

Explanation

The simple syntax of “zone prefix” command is

zone prefix gatekeeper-name e164-prefix [gw-priority priority gw-alias,…]

For example, the command “zone prefix SJ 408 gw-priority 6 SJ1“

SJ is the gatekeeper-name, 408 is the E164-prefix area code, 6 is the priority and SJ1 is the GW-alias

The [gw-priority priority gw-alias,…] part defines how the gatekeeper selects gateways in its local zone for calls to numbers beginning with prefix e164-prefix. The priority ranges from 0 to 10, where 0 prevents the gatekeeper from using the gateway gw-alias for that prefix and 10 places the highest priority on gateway gw-alias. The default is 5.

By assigning SJ2 a priority value higher than that of SJ1, SJ2 will be the first choice when making call to this zone.

Question 2

Refer to the H.323 message in the exhibit. What is the gateway doing with the gatekeeper?

value RasMessage ::= registrationRequest : { requestSeqNum 32633 protocolIdentifier { 0 0 8 2250 0 4} discoveryComplete FALSE callSignalAddress { } rasAddress { ipAddress : { ip ‘0A038201’H port 53852 } } terminalType { mc FALSE undefinedNode FALSE } gatekeeperIdentifier {“HQ”} endpointVendor { vendor { t35countrycode 181 t35Extension 0 manufacturerCode 18 } } timeToLive 60 keepAlive TRUE endpointIdentifier {“8452AEB4 00000002″} willSupplyUUIEs FALSE maintainConnection TRUE }

A. initial registration
B. full registration
C. lightweight registration
D. registration retry

Answer: C

Explanation

For the first time the gateway registers with the gatekeeper, it uses full registration. Prior to H.323 Version 2, Cisco gateways re-registered with the gatekeeper every 30 seconds. Each registration renewal used the same process as the initial registration, even though the gateway was already registered with the gatekeeper. This behavior generated considerable overhead at the gatekeeper. So from H.323 version 2, gateways can re-register with the gatekeeper using lightweight registration (it still requires the full registration process for initial registration, but uses an abbreviated renewal procedure to update the gatekeeper and minimize overhead).

An endpoint’s registration with a gatekeeper may have a limited life span. The gatekeeper specifies the registration duration for an endpoint by including a timeToLive field in the Registration Confirm (RCF) message. After the specified length of time, the registration is considered expired. The endpoint must periodically send a Registration Request (RRQ) having the keepAlive bit set prior to the expiration time. Such a message may include a minimum amount of information as described in H.225.0 and is known as a lightweight RRQ.

In the exhibit above, we can see the keepAlive bit is set to TRUE -> this is a lightweight RRQ.

Question 3

In which three RAS messages is the technology prefix sent? (Choose three.)

A. GRQ
B. RRQ
C. RCF
D. IRR
E. IRQ

Answer: A B E

Explanation

The Cisco gatekeeper uses technology prefixes to group endpoints of the same type together. It uses the technology prefix appended in the called number to select the destination gateway or zone.

This method prepends a technology prefix to the called number matched by the dial-peer. It is not used for registration, but for call setup with the Cisco gatekeeper. For example, called number 5551234 becomes 1#5551234.

The technology prefix registration information is sent to the Cisco gatekeeper in the RAS Registration Request (RRQ) message. For example:

GWY-B1(config)#interface ethernet 0/0
GWY-B1(config-if)#h323-gateway voip tech-prefix 1#

-> B is correct.

Question 4

Refer to the output from the debug h225 asn1 command in the exhibit. You have configured a gatekeeper with two local zones, hq and br. You want the gateway at the branch location to register with zone BR. What needs to be corrected in the branch gateway to resolve the issue?

A. Change the IP address in the h323-gateway voip id command.
B. Change the gatekeeper-id in the h323-gateway voip id command.
C. Add a zone remote for zone BR so the gateway can register with the correct zone.
D. Change the gatekeeper-id and the IP address in the h323-gateway voip id command.

Answer: B

Question 5

You have been asked to deploy a gatekeeper to support CUBE that will connect your organizational domain to the domain of an Internet Telephony Service Provider so that callers can reach the 407 area code. Which configuration will support this function?

A.
gatekeeper
zone local GKVIA acme.com 192.168.10.1
zone remote GK407 ITSP.com 10.10.1.100
zone prefix GK407…….
no shutdown

B.
gatekeeper
zone local GKVIA acme.com 192.168.10.1
zone remote GK407 ITSP.com 10.10.1.100 1719 invia outvia GKVIA
zone prefix GK407 407*
no shutdown

C.
gatekeeper
zone local GKVIA acme.com 192.168.10.1
zone remote GK407 ITSP.com 10.10.1.100 1719 invia GK407 outvia GK407
zone prefix GK407…….
no shutdown

D.
gatekeeper
zone local GKVIA acme.com 192.168.10.1
zone remote GK407 ITSP.com 10.10.1.100 1719 invia GKVIA outvia GKVIA
zone prefix GK407 407*
no shutdown

Answer: D

Question 6

Refer to the exhibit. You have configured a gatekeeper and an IP-IP gateway on the same router. When you look at the output from the show gatekeeper endpoint command, the IP-IP gateway is not registered with the gatekeeper. What needs to be configured to resolve this issue?

A. You need to stop and restart the gateway.
B. You need to add a VoIP dial peer to the configuration.
C. The h323-gateway voip id command has an incorrect IP address.
D. The h323-gateway voip id command has an incorrect gatekeeper ID and IP address.

Answer: B

Question 7

Call Admission control (CAC) is a concept that applies to voice traffic only – not data traffic. Which two types are of Call Admission Control? (Choose two.)

A. resource-based
B. gatekeeper-controlled RSVP
C. local
D. QoS-based

Answer: A C

Explanation

There are 3 types of CAC:
+ Local CAC
+ Measurement Based CAC
+ Resource-Based CAC

For more information about these types, please read: http://www.cisco.com/en/US/docs/ios/solutions_docs/voip_solutions/CAC.html

Question 8

The SJ local zone contains a gatekeeper that controls two gateways, SJ1 and SJ2. Both gateways provide access to area code 408. For the following command strings, which two will be entered into the gatekeeper to give the SJ2 gateway priority over the SJ1 gateway? (Choose two.)

A. zone prefix SJ 408 gw -priority 10 SJ2
B. zone prefix SJ 408 gw-priority 10 SJ1
C. zone prefix SJ 408 gw-priority 6 SJ2
D. zone prefix SJ 408 gw-priority 6 SJ1

Answer: A D

Question 9

You are a Acme network administrator, your new task is to deploy a gatekeeper to support CUBE that will connect your organizational domain to the domain of an Internet Telephony Service Provider so that callers can reach the 407 area code. Which configuration will support this function?

A.
gatekeeper
zone local GKVIA acme.com 192.168.10.1
zone remote GK407 ITSP.com 10.10.1.100
zone prefix GK407 407
no shutdown

B.
gatekeeper
zone local GKVIA acme.com 192.168.10.1
zone remote GK407 ITSP.com 10.10.1.100 1719 invia outvia GKVIA
zone prefix GK407 407*
no shutdown

C.
gatekeeper
zone local GKVIA acme.com 192.168.10.1
zone remote GK407 ITSP.com 10.10.1.100 1719 invia GK407 outvia GK407
zone prefix GK407 407
no shutdown

D.
gatekeeper
zone local GKVIA acme.com 192.168.10.1
zone remote GK407 ITSP.com 10.10.1.100 1719 invia GKVIA outvia GKVIA
zone prefix GK407 407*
no shutdown

Answer: D

Question 10

You are the director of the Acme VoIP network, based on the exhibit. You have a client that is testing a directory gatekeeper in the lab to provide address resolution between two different zones. Two of the commands in the running-config output are incorrect. Which two changes will correct the configuration? (Choose two.)

voicetut# show running-config … ! zone local voicetut acm.com zone local GK-A acme com 172.16.14.44 1719 zone remote GK-B acme.com 172.16.14.99 1719 zone prefix GK-A 770…… zone prefix GK-B 404…. no shutdown ! …

A.
replace
zone local GK-A acme.com 172.16.14.44 1719
with
zone remote GK-A acme.com 172.16.14.44 1719

B.
replace
zone local DGK acme.com
with
zone remote DGK acme.com

C.
replace
zone prefix GK-B 404….
with
zone prefix GK-B 404……..

D.
replace
zone prefix GK-A 770…….
with
zone prefix GK-A 770….

Answer: A D