Question 3 of 52 from exam 300-820-CLCEI: Implementing Cisco Collaboration Cloud and Edge Solutions
Question
When an Expressway-E is configured for static NAT, which Session Description Protocol attribute is modified to reflect the NAT address?
Answers
Explanations
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A. B. C. D.C.
When an Expressway-E is configured for static NAT, the Session Description Protocol (SDP) c-line attribute is modified to reflect the NAT address.
SDP is a protocol used to describe multimedia sessions for the purposes of session initiation, negotiation, and establishment. The c-line attribute in the SDP describes the connection information for the media stream, including the IP address and port number.
When a SIP call traverses a NAT device, the IP address and port number in the SDP c-line must be modified to reflect the public address of the NAT device, otherwise the call will not work. This is because the SDP c-line is used to establish the media stream between the endpoints, and if the IP address in the c-line is incorrect, the media stream will not be established.
When an Expressway-E is configured for static NAT, the public IP address of the NAT device is used to replace the private IP address in the SDP c-line. This ensures that the media stream is properly established between the endpoints.
Therefore, the correct answer is C. SDP c-line.
