NCS 30022303010 NCSP LTE EPC OaM 2 2 Practice Exam
**Question 1. Which LTE EPC element is primarily responsible for allocating IP
addresses to a UE during PDN connectivity?**
A) MME
B) S‑GW
C) P‑GW
D) HSS
Answer: C
Explanation: The Packet Data Network Gateway (P‑GW) assigns an IP address to
the UE when a PDN connection is established.
**Question 2. The interface S1‑MME connects which two network functions?**
A) UE and eNodeB
B) eNodeB and MME
C) MME and S‑GW
D) S‑GW and P‑GW
Answer: B
Explanation: S1‑MME is the control‑plane interface between the eNodeB and the
Mobility Management Entity (MME).
**Question 3. Which protocol is used on the S6a interface for authentication,
authorization, and accounting?**
A) GTP‑C
B) Diameter
,NCS 30022303010 NCSP LTE EPC OaM 2 2 Practice Exam
C) SCTP
D) TCP
Answer: B
Explanation: Diameter carries AAA messages between the MME and the Home
Subscriber Server (HSS) over the S6a reference point.
**Question 4. In LTE EPC, what is the main function of the Serving Gateway
(S‑GW)?**
A) Policy enforcement
B) User‑plane mobility anchor
C) Subscriber authentication
D) Charging record generation
Answer: B
Explanation: The S‑GW acts as the anchor point for the user plane, routing user
data packets and handling mobility between eNodeBs.
**Question 5. Which reference point carries user‑plane traffic between the
eNodeB and the S‑GW?**
A) S1‑U
B) S1‑MME
C) S5/S8
D) SGi
Answer: A
,NCS 30022303010 NCSP LTE EPC OaM 2 2 Practice Exam
Explanation: S1‑U is the user‑plane interface that transports user data between
the eNodeB and the S‑GW.
**Question 6. The Gx interface is used between which two EPC components?**
A) MME and HSS
B) PCRF and P‑GW
C) S‑GW and P‑GW
D) MME and S‑GW
Answer: B
Explanation: Gx carries policy and charging control information from the Policy
and Charging Rules Function (PCRF) to the P‑GW.
**Question 7. Which Diameter application is employed on the S6a interface for
subscription data retrieval?**
A) Credit‑Control Application (CCA)
B) Roaming Application (Ro)
C) Sh Application (Subscriber‑Home)
D) Gx Application
Answer: C
Explanation: The Sh application is used on S6a to query or update subscriber
profile information stored in the HSS.
**Question 8. In the EPC, what does the acronym “PCRF” stand for?**
, NCS 30022303010 NCSP LTE EPC OaM 2 2 Practice Exam
A) Packet Core Routing Function
B) Policy and Charging Rules Function
C) Protocol Control and Routing Facility
D) Performance Control and Reporting Framework
Answer: B
Explanation: PCRF stands for Policy and Charging Rules Function, responsible for
policy control and charging rule enforcement.
**Question 9. Which KPI measures the percentage of successful initial network
attachments of UEs?**
A) Service Request Success Rate
B) Attach Success Rate
C) Bearer Setup Success Rate
D) Session Drop Rate
Answer: B
Explanation: Attach Success Rate indicates how many UE attach attempts succeed
out of the total attempts.
**Question 10. The SGi interface connects the P‑GW to which type of network?**
A) Radio Access Network
B) Core Network
C) External Packet Data Network (PDN)
**Question 1. Which LTE EPC element is primarily responsible for allocating IP
addresses to a UE during PDN connectivity?**
A) MME
B) S‑GW
C) P‑GW
D) HSS
Answer: C
Explanation: The Packet Data Network Gateway (P‑GW) assigns an IP address to
the UE when a PDN connection is established.
**Question 2. The interface S1‑MME connects which two network functions?**
A) UE and eNodeB
B) eNodeB and MME
C) MME and S‑GW
D) S‑GW and P‑GW
Answer: B
Explanation: S1‑MME is the control‑plane interface between the eNodeB and the
Mobility Management Entity (MME).
**Question 3. Which protocol is used on the S6a interface for authentication,
authorization, and accounting?**
A) GTP‑C
B) Diameter
,NCS 30022303010 NCSP LTE EPC OaM 2 2 Practice Exam
C) SCTP
D) TCP
Answer: B
Explanation: Diameter carries AAA messages between the MME and the Home
Subscriber Server (HSS) over the S6a reference point.
**Question 4. In LTE EPC, what is the main function of the Serving Gateway
(S‑GW)?**
A) Policy enforcement
B) User‑plane mobility anchor
C) Subscriber authentication
D) Charging record generation
Answer: B
Explanation: The S‑GW acts as the anchor point for the user plane, routing user
data packets and handling mobility between eNodeBs.
**Question 5. Which reference point carries user‑plane traffic between the
eNodeB and the S‑GW?**
A) S1‑U
B) S1‑MME
C) S5/S8
D) SGi
Answer: A
,NCS 30022303010 NCSP LTE EPC OaM 2 2 Practice Exam
Explanation: S1‑U is the user‑plane interface that transports user data between
the eNodeB and the S‑GW.
**Question 6. The Gx interface is used between which two EPC components?**
A) MME and HSS
B) PCRF and P‑GW
C) S‑GW and P‑GW
D) MME and S‑GW
Answer: B
Explanation: Gx carries policy and charging control information from the Policy
and Charging Rules Function (PCRF) to the P‑GW.
**Question 7. Which Diameter application is employed on the S6a interface for
subscription data retrieval?**
A) Credit‑Control Application (CCA)
B) Roaming Application (Ro)
C) Sh Application (Subscriber‑Home)
D) Gx Application
Answer: C
Explanation: The Sh application is used on S6a to query or update subscriber
profile information stored in the HSS.
**Question 8. In the EPC, what does the acronym “PCRF” stand for?**
, NCS 30022303010 NCSP LTE EPC OaM 2 2 Practice Exam
A) Packet Core Routing Function
B) Policy and Charging Rules Function
C) Protocol Control and Routing Facility
D) Performance Control and Reporting Framework
Answer: B
Explanation: PCRF stands for Policy and Charging Rules Function, responsible for
policy control and charging rule enforcement.
**Question 9. Which KPI measures the percentage of successful initial network
attachments of UEs?**
A) Service Request Success Rate
B) Attach Success Rate
C) Bearer Setup Success Rate
D) Session Drop Rate
Answer: B
Explanation: Attach Success Rate indicates how many UE attach attempts succeed
out of the total attempts.
**Question 10. The SGi interface connects the P‑GW to which type of network?**
A) Radio Access Network
B) Core Network
C) External Packet Data Network (PDN)
