Which of the following indicates a global error in SIP protocol?

Question

Options

• A3xx
• B4xx
• C5xx
• D6xx

• A
  14% (5)
• B
  9% (3)
• C
  3% (1)
• D
  74% (26)

Explanation

6xx Global Failure responses in SIP indicate that a request has definitively failed - not just at one server, but across all possible servers for that destination. When a 6xx response is received, the request should not be retried anywhere else, making it a "global" (final, network-wide) rejection.

Why the distractors are wrong:

• 3xx (Redirection): Not an error at all - it tells the client to try a different address or server.
• 4xx (Client Error): Indicates the problem is with the request itself (bad syntax, unauthorized, not found), not a global failure.
• 5xx (Server Error): Means that specific server couldn't handle the request, but another server might succeed - so it's local, not global.

Memory tip: Think of 6xx as "6 feet under" - the call is completely dead, no resurrection possible. The progression 3→4→5→6 goes from "try elsewhere" → "your fault" → "my fault" → "nobody can help."

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