QUESTION NO: 121
Refer to the exhibit. Which two actions would be initiated by a UAS? (Choose two.)
A. returns a response on behalf of the user to the invitation originator
B. contacts the user when a SIP invitation is received
C. originates the ACK method to indicate that it has received a response to an invitation
D. originates the INVITE method including a description of the session parameters
E. originates the REFER method to initiate call termination
Answer: A,B
Explanation: SIP is a peer-to-peer protocol. The peers in a session are called User Agents (UAs). A user agent can function in one of the following roles:
User agent client (UAC): A client application that initiates a SIP request
User agent server (UAS): A server application that contacts the user when a SIP invitation is received and then returns a response on behalf of the user to the invitation originator
QUESTION NO: 122
Refer to the H.323 message in the exhibit. What is the gateway doing with the gatekeeper?
A. full registration
B. registration retry
C. lightweight registration
D. initial registration
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 Time To Live 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 keep Alive 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 NO: 123
Which dial plan characteristic shows the most obvious improvement by dropping a number translation step?
A. hierarchical design
B. post-dial delay
C. availability
D. scalability
Answer: B
Explanation: Post-dial delay is the time between when the last digit is dialed and the moment the phone rings at the receiving location. In the PSTN, people expect a short post dial delay and to hear ring back within seconds. The more translations, digit manipulations, and lookups that take place, the longer the post dial delay becomes. Overall network design, translation rules, and alternate paths affect post dial delay. Minimize the amount of dial peers and translations to reduce post-dial delay. By dropping a number translation step, the post-dial delay time will be obvious improvement.
QUESTION NO: 124
Refer to the exhibit. Enzo’s Bikes manufactures high end bicycle frames. Until recently they sold only to bicycle shops; however, now they are starting to sell to end users. They need a way to add two additional sales staff and ensure that the senior sales technician always gets the first call. Drew is the senior sales technician. Bob is the newest sales technician. Bob’s phone should always be the last one chosen for incoming sales calls, after Drew and James. Bob’s phone should be chosen first only when Drew and James are busy on calls.
Select the correct dial-peer command set for Bob’s phone.
A. dial-peer voice 3 pots destination-pattern 5555110 preference high
B. dial-peer voice 3 pots destination-pattern 5555110 preference 3 huntstop
C. dial-peer voice 3 pots destination-pattern 5555110 preference 2
D. dial-peer voice 3 pots destination-pattern 5555110 preference 0
E. dial-peer voice 3 pots destination-pattern 5555110 preference firstlast
Answer: C
Explanation: To give specific dial peers in the pool a preference over other dial peers, you can configure the preference order for each dial peer by using the preference command. The router attempts to place a call to the dial peer with the highest preference. The lower the preference number, the higher the priority. The highest priority is given to the dial peer with preference order
0. If the same preference is defined in multiple dial peers with the same destination pattern, a dial peer is selected randomly. Therefore, by setting the preference of Bob’s dial-peer to 2 we guarantee Bob will be the last one to receive the call.
QUESTION NO: 125
Which three services are supported by CUBE when supporting H323-to-SIP calls? (Choose three.)
A. codec transparent support
B. media flow-through
C. Transport Layer Security
D. H.261, H.263, and H.264 video codecs
E. media flow-around
F. SIP cause codes
Answer: A,B,C
Explanation: Media flow around is not supported on the Cisco Unified Border Element (CUBE) for Configuring H.323-to-SIP Connections. The CUBE is always involved in the call setup (signaling) portion of the call, but the media (RTP bearer stream) may flow through the CUBE or be routed around the platform. Media flow through is used to support many of the features available like IP address translation and IP address hiding. For “Media flow through” option, the media packets are passed through the CUBE, they will get terminated and re-originate with CUBE’s IP address and port number, so here we cannot find the original gateway’s ip address. This is one of the security features in the CUBE. B is Correct The transparent codec is unique to the Cisco Unified Border Element. Configuring codec transparent on the Cisco Unified Border Element allows it to pass through codec’s that it understands, but it does not force the negotiation of any particular codec-codec negotiation is left to the two endpoints. Only codec’s that are supported on the Cisco Unified Border Element can be passed between the two call legs. Codec Transparent was not supported till Cisco IOS Release 12.4(11)T. A is correct. Transport Layer Security (TLS) is a security protocol that enables encrypted network communications. TLS on CUBE can be configured on a per-leg basis in order to allow a TLS to non-TLS SIP call. For example, CUBE uses IPSec in order to secure signaling and support calls from H.323 to SIP with the H.323 leg, while the SIP leg uses TLS. C is correct
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