Which of the following statements is true about image sampling?
A
Explanation:
YUV 4:2:0 subsamples chroma by a factor of two in both horizontal and vertical dimensions, reducing
total data to half of the full-resolution YUV 4:4:4 format.
Which of the following header fields is used to indicate the route of a response message?
A
Explanation:
The Via header records each hop a request takes and is used to route the corresponding response
back along the same path.
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In a SIP-only multipoint conference, when a participant sends the presentation, the system uses the
____________ protocol for presentation. (Enter the abbreviation.)
BFCP
Explanation:
In SIP-only multipoint conferences, presentation content is delivered using the Binary Floor Control
Protocol (BFCP), which handles floor control and content distribution.
The start line of a SIP response consists of three parts: method (Method), request URI (Request-URI),
and protocol version (SIP-VERSION).
B
Explanation:
A SIP response start line is a Status-Line containing the SIP version, status code, and reason phrase -
not the method and Request-URI.
SIP and SDP are independent of each other. SIP can implement multimedia calls independently to
add new applications or media easily.
B
Explanation:
SIP relies on SDP for session description in multimedia calls; it cannot negotiate media parameters
independently of SDP.
SIP is an application-layer protocol independent of the transport-layer protocols. It can be carried
over different transport protocols, such as UDP, TCP, TLS, and SCTP. Currently, SCTP is the most
commonly used transport-layer protocol.
B
Explanation:
While SIP is transport-agnostic and can run over UDP, TCP, TLS, or SCTP, UDP remains the
predominant transport - SCTP is not the most commonly used.
In the SIP protocol, the Via header field indicates the route of the subsequent response message.
A
Explanation:
The Via header tracks each hop of the request and is used to guide the response back along the same
path.
The Record-Route header field indicates the route of a request.
A
Explanation:
The Record-Route header is inserted by proxies to advertise their desired route for subsequent
requests in the dialog.
During a point-to-point call between different GKs, the local GK sends an LRQ request to the
neighboring GK to query the information about the called node.
A
Explanation:
In H.323, when a gatekeeper needs to locate an endpoint outside its zone, it issues a
LocationRequest (LRQ) to the neighboring gatekeeper to retrieve the called party’s address.
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Assume endpoints T1 and T2 are registered with the same SC node zone (signaling routing is disabled
on the SC). After T1 calls the number of T2 using H.323, T1 and T2 communicate with each other. In
this process, a total of ____________ TCP connection(s) need to be established between T1 and T2.
(Enter an Arabic numeral.)
2
Explanation:
H.323 sets up one TCP connection for H.225 call signaling (Q.931) and a second TCP connection for
the H.245 control channel, totaling two TCP connections.