In troubleshooting SSL issues, what does packet capture help you understand?

Packet capture is a valuable tool in troubleshooting SSL issues, as it provides insight into the state of the SSL/TLS connection between the client and server. Specifically, by analyzing the captured packets, you can observe how SSL handshakes are occurring, which includes inspection of the certificates being exchanged. This helps determine if the correct certificate is presented by the server during the SSL handshake, whether the certificate is valid, including its status and expiration, and if it is properly configured for the site the client is trying to access.

Understanding the state of the certificate at the time of the client request is crucial in diagnosing issues where a client may not be able to establish a secure connection. For example, expired certificates or misconfigured trusted certificate authorities might lead to connection failures or browser warnings. Hence, packet capture can pinpoint these issues effectively.

The other choices address different aspects of network troubleshooting. Assessing whether traffic is being delivered successfully pertains more to general network connectivity than specifically to SSL issues. Identifying if a user is blocked from accessing sites focuses on access permissions rather than SSL configuration. Lastly, optimizing traffic load and compression relates to performance enhancements rather than the security layer of SSL interactions. Therefore, understanding the state of the certificate is central to resolving SSL issues.