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Common Technical Interview Questions and Answers Update on March 30, 2020

Question 51: True or false: Microservices are only meant for smaller businesses.
A. True
B. False
Correct Answer: B. False
Explanation: Despite the “micro” in its name, larger businesses have taken to this design fairly well. Amazon and Netflix are just two of the famously large enterprises that have pioneered this style of architecture.

Question 52: Which Transport layer protocol and ports do Skinny and SIP signaling protocols use for communications between Cisco Unified Communications Manager (CUCM) and IP phones?
A. TCP 2000, TCP 5060
B. UDP 2000, UDP 5060
C. TCP 2000, TCP and UDP 5060
D. TCP 1723, UDP 5060
Correct Answer: A. TCP 2000, TCP 5060
Explanation: TCP port 2000 is used by Cisco’s Skinny Client Control Protocol (SCCP), while SIP uses TCP port 5060. IP phones, such as the 7900 series and ATA 186, use SCCP by default, while IP phones like the Cisco 9951, 9971 and ATA 187 use SIP. For more information on Transport protocols and ports, see Table 6 on this CUCM site.

Question 53: Where would you go to configure a SIP Route Pattern?

Where would you go to configure a SIP Route Pattern?

Where would you go to configure a SIP Route Pattern?

A. System > SIP Route Pattern
B. Call Routing > Route/Hunt > Route Pattern
C. Call Routing > SIP Route Pattern
D. Call Routing > Dial Rules > SIP Dial Rules
Correct Answer: C. Call Routing > SIP Route Pattern
Explanation: SIP Route Patterns are accessible via the Call Routing > SIP Route Patten menu. SIP Route Patterns are used by CUCM to route or block internal and external phone calls.

Question 54: Which of the following codecs are recommended for LAN and WAN usage?
A. LAN – G.729, WAN – G.711
B. LAN – G.711, WAN – G.711
C. WAN – G.729, LAN – G.771
D. WAN – G.729, LAN – G.711
Correct Answer: D. WAN – G.729, LAN – G.711
Explanation: G.711 is the preferred codec for LAN VoIP communications, as it provides high-quality voice at the expense of just over 80 Kbps bandwidth per session, which is negligible for today’s multigigabit LAN speeds.

G.729, on the other hand, provides high voice compression and very small bandwidth requirements of just 8 Kbps per session. The trade-off with G.729 is the voice quality, which is similar to mobile phones. G.729 is considered ideal for VoIP communication over WAN links where there are usually bandwidth restrictions or limited bandwidth availability.

Question 55: What route pattern wildcard character is used to terminate the interdigit timeout delay?
A. !
B. .
C. #
D. 0
Correct Answer: C. #
Explanation: Interdigit timeout delay is the time the user has between dialing digits in a phone number. When dialing, Cisco CallManager will wait for a specified time every time a digit is pressed until the interdigit timeout delay is reached. At that point, CallManager dials the number inserted as it understands that there are no more digits to be dialed and the user has entered the destination number in full.

The hash symbol “#” is used to speed up this process and terminate the interdigit timeout delay by informing CallManager that the destination number has been dialed completely and it should immediately start dialing the number entered. The interdigit timeout delay is usually configured for three to four seconds. Longer interdigit timeout delay might give the user the impression that the VoIP system is slow or has a problem.

Question 56: Which command is used to test translation rules on a Cisco IOS voice gateway?
A. Show translation-rule
B. Test translation-rule
C. Debug voice ccapi inout
D. Test translate parameter
Correct Answer: B. Test translation-rule
Explanation: Translation rules allow the manipulation of digits for both incoming and outgoing calls. Translation rules are very powerful and flexible tools that help overcome limitations due to numbering plan, site location, telecommunication provider limitations and more.

Testing a translation pattern allows us to confirm that the digits received by either the end user or telecommunication provider are manipulated in the correct way.

Question 57: Which of the following Dynamic Host Configuration Protocol (DHCP) options is used to help IP phones locate and register to CallManager or CallManager Express?
A. option 123
B. option 69
C. option 150
D. option 68
Correct Answer: C. option 150
Explanation: DHCP option 150 is used to identify the CallManager or CallManager Express IP address and is a critical DHCP parameter for any Cisco VoIP network. An example configuration of a DHCP server below shows the correct usage of the option 150:

! ip dhcp pool VoIP_Network network default-router option 150 ip dns-server domain-name lease 8

Question 58: If route patterns 7XXX, 71XX, 712X and 7109 exist in the call route database and a user dials 7123, which pattern will be matched?
B. 7109
C. 712X
D. 71XX
Correct Answer: C. 712X
Explanation: CallManager will use the route pattern with the most matching digits. In this case, route pattern 712X has the most matching digits.

Question 59: When configuring calling privileges on Cisco Unified Communications Manager Express, which of the following is used?
A. Translation Patterns
B. Dial-peers
C. Access-lists
D. COR lists
Correct Answer: D. COR lists
Explanation: COR (Class of Restrictions) lists are a voice gateway feature used to assign calling privileges to users. With COR lists, we have the ability to deny calls based on the incoming and outgoing CORs configured on the dial-peers.

Question 60: Which of the following is the mandatory codec every VoIP endpoint device must support?
A. G.711
B. G.729
C. G.723
Correct Answer: A. G.711
Explanation: G.711 is a mandatory codec used and supported by every VoIP endpoint device. G.711 requires around 80 Kbps bandwidth per call (includes IP overhead) and has similar quality to a landline phone call. G.711 is usually used for VoIP calls where all IP phones are located on the same LAN/network, while G.729 requires 32 Kbps (includes IP overhead) and is considered the preferred codec for VoIP calls over WAN links or links with limited bandwidth.

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