101 · Question #504
HTTPs traffic is not working properly. What is the likely reason for the issue?
The correct answer is C. The server is not listening on TCP 443. HTTPS traffic uses TCP port 443, and if the server is not listening on that port, HTTPS connections will fail.
Question
HTTPs traffic is not working properly. What is the likely reason for the issue?
Exhibit
Options
- A
- 0 0.0 0 is an invalid address in netstat.
- B
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-
- 0.0 80 should be in an active stale
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-
- CThe server is not listening on TCP 443
- DThe server is not listening on UDP 80
How the community answered
(42 responses)- A2% (1)
- C95% (40)
- D2% (1)
Why each option
HTTPS traffic uses TCP port 443, and if the server is not listening on that port, HTTPS connections will fail.
0.0.0.0 is a valid wildcard listen address in netstat, meaning the service is accepting connections on all interfaces, so this is not an error condition.
HTTP on port 80 being in any state is unrelated to an HTTPS failure on port 443; the two services are independent.
HTTPS (HTTP over TLS/SSL) operates exclusively on TCP port 443 by default. If a netstat or port check reveals the server is not listening on TCP 443, incoming HTTPS requests will be refused or time out, causing the observed traffic failure. Confirming the service is bound to TCP 443 is the first diagnostic step for HTTPS connectivity issues.
HTTPS uses TCP, not UDP, and port 80 is for plain HTTP, not HTTPS; a server not listening on UDP 80 has no bearing on HTTPS traffic.
Concept tested: HTTPS protocol port and transport layer requirements
Source: https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml
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