Q. Which information in the application layer in the Diameter User Authorization Answer response for the first Diameter UAR request that is sent to HSS?
a) Server Capabilities
b) P-CSCF address
c) S-CSCF Address
d) Supplementary Services
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Correct answer: Letter a.
Server Capabilities are returned in the User-Authorization-Answer (UAA) from the HSS in response to a User-Authorization-Request (UAR) sent by the I-CSCF. These capabilities guide the I-CSCF in selecting an appropriate S-CSCF based on what services the user is authorized to access.
Q. Which information in the application layer in the Diameter User Authorization Answer response for the first Diameter UAR request that is sent to HSS?
a) 
Server Capabilities
→ Correct. The Server-Capabilities AVP includes details such as mandatory and optional service profiles required for routing to a compatible S-CSCF.
b) 
P-CSCF address
→ Incorrect. The P-CSCF address is learned earlier, typically during the initial SIP registration via the UE’s configuration or DHCP, not through the UAR/UAA exchange.
c) S-CSCF Address
→ Incorrect. The S-CSCF selection is made after receiving server capabilities, and its address is sent in Server-Assignment Answer (SAA), not UAA.
d) Supplementary Services
→ Incorrect. These services are part of the user profile, retrieved via Multimedia-Auth-Request (MAR) or Server Assignment Request (SAR), not the UAR/UAA.
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