How can you identify TLS alert messages and their meaning?

• A. TLS Alert messages in the TLS layer; the alert description indicates the reason, such as bad_record_mac, handshake_failure.
• B. TLS alerts indicate HTTP status codes.
• C. TLS alerts are shown in ARP tables.
• D. TLS alerts are not captured.

Answer: (A)

TLS alert messages are control signals within the TLS protocol used to indicate warnings or fatal errors during a session. They live in the TLS layer, not in HTTP or the data link layer, and they can be observed in a packet capture even when the rest of the TLS traffic is encrypted.

You can identify them by looking for a TLS record with the content type labeled as an Alert. In Wireshark this shows up as a TLS Alert message, and you’ll see the alert level (warning or fatal) together with a description such as bad_record_mac or handshake_failure. The description explains the reason for the alert—for example, bad_record_mac means the integrity check failed on a record, suggesting a mismatch in encryption or tampering, while handshake_failure means the handshake could not be completed due to incompatible parameters or certificate issues.

These alerts are not HTTP status codes, and they aren’t shown in ARP tables. They are specific to TLS and can be decoded from the capture, even if the application data remains encrypted.