How can you identify HTTP keep-alive usage and the number of requests per connection?

• A. Look for multiple HTTP requests/responses on the same TCP stream and check for Connection: keep-alive headers.
• B. Check for HTTP status codes in responses.
• C. Look for DNS EDNS0 OPT records.
• D. Look for TCP window scale options.

Answer: (A)

HTTP keep-alive means using the same TCP connection to handle multiple HTTP requests and responses. You identify this by seeing several HTTP messages exchanged over one TCP stream instead of opening a new connection for each request. In practice, you look for multiple HTTP requests and the corresponding responses sharing the same TCP connection, and you check for the header that signals persistence, such as Connection: keep-alive. Counting how many request/response pairs appear on that single connection gives you the number of requests per connection. In HTTP/1.1, connections are persistent by default, so the presence of multiple messages on one stream already indicates keep-alive usage, even if the explicit header isn’t seen every time. The other options don’t reveal persistence: status codes show outcomes, not reuse; DNS EDNS0 records are about DNS, not HTTP; and TCP window scale options pertain to transport performance, not whether the HTTP connection is reused.