NCS 20022301010 NCSS LTE RA OaM 2 2 Practice Exam
**Question 1.** Which functional split separates the EPC’s control plane from the
RAN’s user plane?
A) S1-MME / S1-U split
B) X2 / Xn split
C) PDCP/RLC split
D) MAC/PHY split
Answer: A
Explanation: The S1-MME interface carries control‑plane signaling while S1‑U
carries user‑plane GTP‑U traffic, defining the primary EPC–RAN split.
**Question 2.** In LTE, the S1‑AP protocol runs over which transport layer?
A) UDP over IP
B) SCTP over IP
C) TCP over IP
D) RTP over IP
Answer: B
Explanation: S1‑AP is encapsulated in SCTP (Stream Control Transmission Protocol)
to provide reliable, ordered delivery for control‑plane messages.
**Question 3.** Which message is used by the eNodeB to request a handover to
a target eNodeB?
A) Handover Request
B) Handover Command
, NCS 20022301010 NCSS LTE RA OaM 2 2 Practice Exam
C) Handover Preparation Information
D) Handover Cancel
Answer: A
Explanation: The source eNodeB sends a Handover Request to the target eNodeB
(via X2) to initiate the handover procedure.
**Question 4.** The GTP‑C protocol primarily handles:
A) User‑plane data forwarding
B) Control‑plane signaling for tunnel creation
C) Radio resource allocation
D) Encryption of user traffic
Answer: B
Explanation: GTP‑C (Control) is used to set up, modify, and delete GTP tunnels,
whereas GTP‑U carries user data.
**Question 5.** Which Diameter application is used for authentication,
authorization, and accounting in LTE?
A) Credit Control Application (CCA)
B) Network Access Server (NASREQ)
C) Mobile IPv4 Application
D) 3GPP S6a/S6d
Answer: D
, NCS 20022301010 NCSS LTE RA OaM 2 2 Practice Exam
Explanation: The 3GPP S6a (for MME‑HSS) and S6d (for PCRF) Diameter
applications support AAA functions in LTE.
**Question 6.** During an Initial Attach, which entity first validates the UE’s
identity?
A) SGW
B) MME
C) HSS
D) eNodeB
Answer: B
Explanation: The MME receives the Attach Request, validates the UE’s identity
(e.g., IMSI) and initiates authentication with the HSS.
**Question 7.** A Dedicated Bearer is typically established for:
A) Default IP connectivity only
B) Voice over LTE (VoLTE) or QoS‑sensitive traffic
C) SMS transmission
D) Broadcast services
Answer: B
Explanation: Dedicated Bearers provide specific QoS parameters (e.g., low latency
for VoLTE) beyond the default bearer.
**Question 8.** Which KPI reflects the efficiency of bearer setup in the NCSS?
, NCS 20022301010 NCSS LTE RA OaM 2 2 Practice Exam
A) Handover Success Rate
B) Attach Success Rate
C) Bearer Setup Success Ratio
D) RRC Connection Failure Rate
Answer: C
Explanation: Bearer Setup Success Ratio measures how many bearer
establishment attempts succeed, indicating NCSS efficiency.
**Question 9.** In the NCSS, what does the “Load Distribution” parameter affect?
A) Number of eNodeBs that can connect simultaneously
B) Allocation of processing resources among attached eNodeBs
C) Maximum throughput per bearer
D) Frequency band selection
Answer: B
Explanation: Load Distribution defines how the NCSS balances CPU and memory
resources among multiple eNodeBs to avoid overload.
**Question 10.** Which alarm indicates a failure of the S1‑U user‑plane tunnel?
A) S1‑AP Link Down
B) GTP‑U Path Error
C) Diameter Timeout
D) X2 Handover Failure
**Question 1.** Which functional split separates the EPC’s control plane from the
RAN’s user plane?
A) S1-MME / S1-U split
B) X2 / Xn split
C) PDCP/RLC split
D) MAC/PHY split
Answer: A
Explanation: The S1-MME interface carries control‑plane signaling while S1‑U
carries user‑plane GTP‑U traffic, defining the primary EPC–RAN split.
**Question 2.** In LTE, the S1‑AP protocol runs over which transport layer?
A) UDP over IP
B) SCTP over IP
C) TCP over IP
D) RTP over IP
Answer: B
Explanation: S1‑AP is encapsulated in SCTP (Stream Control Transmission Protocol)
to provide reliable, ordered delivery for control‑plane messages.
**Question 3.** Which message is used by the eNodeB to request a handover to
a target eNodeB?
A) Handover Request
B) Handover Command
, NCS 20022301010 NCSS LTE RA OaM 2 2 Practice Exam
C) Handover Preparation Information
D) Handover Cancel
Answer: A
Explanation: The source eNodeB sends a Handover Request to the target eNodeB
(via X2) to initiate the handover procedure.
**Question 4.** The GTP‑C protocol primarily handles:
A) User‑plane data forwarding
B) Control‑plane signaling for tunnel creation
C) Radio resource allocation
D) Encryption of user traffic
Answer: B
Explanation: GTP‑C (Control) is used to set up, modify, and delete GTP tunnels,
whereas GTP‑U carries user data.
**Question 5.** Which Diameter application is used for authentication,
authorization, and accounting in LTE?
A) Credit Control Application (CCA)
B) Network Access Server (NASREQ)
C) Mobile IPv4 Application
D) 3GPP S6a/S6d
Answer: D
, NCS 20022301010 NCSS LTE RA OaM 2 2 Practice Exam
Explanation: The 3GPP S6a (for MME‑HSS) and S6d (for PCRF) Diameter
applications support AAA functions in LTE.
**Question 6.** During an Initial Attach, which entity first validates the UE’s
identity?
A) SGW
B) MME
C) HSS
D) eNodeB
Answer: B
Explanation: The MME receives the Attach Request, validates the UE’s identity
(e.g., IMSI) and initiates authentication with the HSS.
**Question 7.** A Dedicated Bearer is typically established for:
A) Default IP connectivity only
B) Voice over LTE (VoLTE) or QoS‑sensitive traffic
C) SMS transmission
D) Broadcast services
Answer: B
Explanation: Dedicated Bearers provide specific QoS parameters (e.g., low latency
for VoLTE) beyond the default bearer.
**Question 8.** Which KPI reflects the efficiency of bearer setup in the NCSS?
, NCS 20022301010 NCSS LTE RA OaM 2 2 Practice Exam
A) Handover Success Rate
B) Attach Success Rate
C) Bearer Setup Success Ratio
D) RRC Connection Failure Rate
Answer: C
Explanation: Bearer Setup Success Ratio measures how many bearer
establishment attempts succeed, indicating NCSS efficiency.
**Question 9.** In the NCSS, what does the “Load Distribution” parameter affect?
A) Number of eNodeBs that can connect simultaneously
B) Allocation of processing resources among attached eNodeBs
C) Maximum throughput per bearer
D) Frequency band selection
Answer: B
Explanation: Load Distribution defines how the NCSS balances CPU and memory
resources among multiple eNodeBs to avoid overload.
**Question 10.** Which alarm indicates a failure of the S1‑U user‑plane tunnel?
A) S1‑AP Link Down
B) GTP‑U Path Error
C) Diameter Timeout
D) X2 Handover Failure
