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Test your basic knowledge |
CCNA Voice - 3
Start Test
Study First
Subjects
:
cisco
,
it-skills
,
ccna
Instructions:
Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can
study here
.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.
This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. Using G.729 - just __ conversions from D/A cause the MOS score to decrease rapidly but __ is less resilient
2 - G.723.1
echo tail - 25
<1%
last packet - voice
2. Voice samples are packed into the___ ___ of a UDP/RTP packet and thus the network header overhead would be __.
payload field - lower
iLBC
G.728
2 - G.723.1
3. ___describes CELP compression that enables __ to be coded into _ Kbps streams;
sizing
person - computer
7 - compressed
G.729 - voice - 8
4. Is the amount of time it takes to actually place a bit or byte onto an interface. Its influence on delay is relatively minimal.
Propagation delay
Jitter - interarrival - packet-based
Handling delay - queuing delay
Serialization delay
5. Customers that have almost unlimited bandwidth - however - consider __ a worthwhile mechanism to enhance reliability and voice quality - mechanism makes it more probable that one of the packets will make the journey from sender to receiver
amplitude - hangover
sequence number and timestamp
G.729 - voice - 8
forward error correction (FEC)
6. VAD detects a drop-off of speech ___ - it waits a fixed amount of time before it stops putting speech frames in packets. This fixed amount of time is known as __ ( when the person stops talking)
amplitude - hangover
sequence information - time-stamping
sequence number and timestamp
ITU-T - 150
7. Bob@nextdoorneighbor.com is a __ entry but coverts then to an __ address
7 - compressed
compression - decompression
jitter buffer
DNS - IP
8. __ builds in some reliability to the connectionless __ protocol - enables reliability with out using the overhead of __ - what protocol send multiples of the same packet __
Reliable User Data Protocol (RUDP) - UDP - TCP - RUDP
G.711 - PCM - PSTN or PBX(voip networks)
7 - compressed
echo tail - 25
9. __ is not wasting __ when there is no sound to transmit. At least __ % is wasted
VAD - bandwidth - 50
<1%
amplitude - hangover
tandom encoding
10. __is characterized as the amount of time it takes for speech to exit the speaker's mouth and reach the listener's ear.
MOS - subjective -1 - 5
VAD - bandwidth - 50
2 - G.723.1
Latency
11. __ describes __ coding at __ - __ - __ and __ Kbps; you also can interchange ADPCM voice between packet voice and public phone or PBX networks
echo tail - 25
busy house
jitter
G.726 - ADPCM - 40 - 32 - 24 - 16
12. Another compression method used often is ____ . A commonly used instance of this is ITU-T __ - which encodes using 4-bit samples - giving a transmission rate of __ Kbps.
adaptive differential pulse code modulation (ADPCM) - G.726 - 32
echo tail - 25
G.723.1 speech or audio - 6.3 - 5.3
G.726 - ADPCM - 40 - 32 - 24 - 16
13. The jitter buffer found within Cisco IOS ___ is considered a __ queue. This queue can grow or shrink exponentially depending on the interarrival time of the __ packets.
echo cancelers - software - DSP
software - dynamic - RTP
tandom encoding
QoS
14. Propagation delay in conjuction with handeling delay can cause noticeable
begins - front-end speech clipping.
2 - G.723.1
sizing
speech degradation
15. How does G.729 header go __/__/__
IP - RTP - UDP
jitter
sequence information - time-stamping
Propagation delay
16. Echo cancellers are limited by the total amount of time they wait for the reflected speech to be received __ __. A good time to configure is __ms
queuing - unacceptable
echo tail - 25
sizing
IP - RTP - UDP
17. __ Kbps low-delay variation of CELP voice compression 16 kbps
forward error correction (FEC)
G.728
MOS - subjective -1 - 5
G.711 - PCM - PSTN or PBX(voip networks)
18. __ __ conceals interarrival packet delay variation.
DNS - IP
jitter
IP/RTP/UDP - delay - quality - constrained
jitter buffer
19. Is the variation of packet interarrival time.
purchase leased lines - purchase VPN and use access code - OR put voice on data network
G.723.1 speech or audio - 6.3 - 5.3
amplitude - hangover
jitter
20. __ Describes a compression technique that you can use to compress ___or other __ signal components of multimedia service at a low bit rate - MP-MLQ provides greater quality at __ Kbps - CELP provides flexibility at __Kbps
iLBC
groups payload - qos - combining
G.723.1 speech or audio - 6.3 - 5.3
sequence information - time-stamping
21. It has a large header of __ bytes - Size of headers IP/RTP/UDP
concealment strategy
last packet - voice
40 - 20 - 8 - 12
<1%
22. To reduce the overall ___ overhead introduced by the 54-byte header - multiple voice samples can be packed into a single Ethernet frame to transmit. Although this can increase the voice ___ - increasing this count can improve the overall voice___ - e
DNS - IP
250 - 250 - 500
IP/RTP/UDP - delay - quality - constrained
sizing
23. What do you use to compress RTP header to 2 or 4 bytes
CRTP
sizing
iLBC
G.711 - PCM - PSTN or PBX(voip networks)
24. The difference between when the packet is expected and when it is actually received is __. - exists only in __ ___ networks
IP
VAD - bandwidth - 50
Echo
Jitter - interarrival - packet-based
25. Who scored highest in the MOS
MOS - subjective -1 - 5
G.711 PCM
Propagation delay
IP
26. RTCP provides support for real-time conferencing of __ of any size within an Internet - does not send __ - offers __and supports __ media streams
IP - RTP - UDP
echo cancelers - software - DSP
sequence number and timestamp
groups payload - qos - combining
27. RTP uses the __ __ to determine whether the packets are arriving in order - and it uses the __ __ information to determine the interarrival packet time (jitter).
Serialization delay
iLBC
sequence information - time-stamping
continuous media - timing reconstruction
28. RTP consists of a __ __ and a control part the called __
echo tail - 25
iLBC
G.729 - voice - 8
data part - RTP Control Protocol (RTCP).
29. __ __ replays the last packet received
adaptive differential pulse code modulation (ADPCM) - G.726 - 32
concealment strategy
compression - decompression
busy house
30. You hear your own voice in the background ( 4wire)
RTP is Realtime Transport Protocol - delay sensitive
queuing - unacceptable
sequence information - time-stamping
Echo
31. If a packet is lost What is replayed? packet loss is common in data networks but not in __
last packet - voice
person - computer
queuing - unacceptable
Serialization delay
32. What are 3 things you can do if they want to implement a corporate dial plan
purchase leased lines - purchase VPN and use access code - OR put voice on data network
dial plan
VAD - bandwidth - 50
jitter buffer
33. Preferred codec for skype - PC to phone apps - A free speech codec suitable for robust voice communication over IP.
iLBC
RTP is Realtime Transport Protocol - delay sensitive
IP
tandom encoding
34. How many times can a digital to analog conversion in my network and PSTN total network happen - __ speech is less robust conversion
ITU-T - 150
jitter
Latency
7 - compressed
35. This adaptation of jitter buffer __ is effective in compensating for delays.
software - dynamic - RTP
PSQM - objective - computer
sizing
IP/RTP/UDP - delay - quality - constrained
36. Satellite transmission takes approximately __ ms for a transmission to reach the satellite and another __ ms for it to come back down to Earth. This results in a total delay of __ ms.
speech degradation
250 - 250 - 500
person - computer
tandom encoding
37. __ is an _ measurement of voice quality and the __ measures the voice
MOS - subjective -1 - 5
Echo
PSQM - objective - computer
250 - 250 - 500
38. Proxy server is not required in an __ based system
RTP timestamps - jitter
payload field - lower
IP
QoS
39. PCM and ADPCM are examples of __ __
G.723.1 speech or audio - 6.3 - 5.3
RTP timestamps - jitter
waveform codecs
IP - RTP - UDP
40. The problem with VAD is detecting when speech __. This is known as__ Usually - the person listening to the speech does not notice this cut off because it did not record and transmit any codec.
Echo
begins - front-end speech clipping.
concealment strategy
<1%
41. __ __ occurs when you have more than one compression/decompression cycle for each phone call and Voice degradation occurs
2 - G.723.1
G.711 PCM
forward error correction (FEC)
tandom encoding
42. In an unmanaged - congested network - ___delay can add up to two seconds of delay (or result in the packet being dropped). This lengthy period of delay is___ in almost any voice network. delay)
queuing - unacceptable
Serialization delay
DNS - IP
G.729 - voice - 8
43. __ recommends no more than __ms delay one-way transmission
waveform codecs
speech degradation
ITU-T - 150
busy house
44. Simplify the router - use H.323 gatekeeper or voice managers to avoid __ __
tandem compression
jitter
person - computer
source codecs
45. __ the 64 Kbps __ voice coding technique - This is used for the digital voice delivery in the __ or __
PCM - speech - header - information
G.711 - PCM - PSTN or PBX(voip networks)
groups payload - qos - combining
dial plan
46. __ is a __test given to listeners. The listeners give each sample of speech material a rating of __ (bad) to __ (excellent)
jitter
source codecs
ends - begin - background noise - signal-to-noise threshold
MOS - subjective -1 - 5
47. On a voip link What is the max packet loss
IP - RTP - UDP
PCM - speech - header - information
<1%
data part - RTP Control Protocol (RTCP).
48. To make audio and video work with RTP what do you need. 2 things
sequence number and timestamp
payload field - lower
Reliable User Data Protocol (RUDP) - UDP - TCP - RUDP
QoS
49. Caused by the length a signal must travel via light in fiber or electrical impulse in copper-based networks.
forward error correction (FEC)
amplitude - hangover
Propagation delay
G.711 PCM
50. PSQM was developed to 'hear' impairments caused by __ and __ and not packet loss or jitter
purchase leased lines - purchase VPN and use access code - OR put voice on data network
ITU-T - 150
compression - decompression
busy house