300-445 Question 197
Select 3You are diagnosing a web application performance issue for an enterprise network. Users have reported slow page load times. Using a browser waterfall chart, you observe extended time in the 'Waiting (TTFB)' phase for multiple resources. Which of the following are the most likely causes for this issue?
- A
High server-side processing time
- B
Network congestion between the client and server
- C
Large image sizes in the web application
- D
Poor DNS resolution performance
- E
Client-side JavaScript execution issues
Show answer and explanation
Correct answers: A, B, D
Explanation
The 'Waiting (TTFB)' phase in a browser waterfall chart measures the time taken for the server to respond after a request is sent. Issues like high server-side processing time, network congestion, and DNS resolution delays directly contribute to this phase. Large image sizes and client-side JavaScript execution do not affect the 'Waiting (TTFB)' phase but instead impact other segments like download or rendering.
- A. Correct.
High server-side processing time can increase the 'Waiting (TTFB)' phase as the server takes longer to generate a response after receiving the request.
- B. Correct.
Network congestion between the client and server can delay the delivery of the response, leading to an extended 'Waiting (TTFB)' phase.
- C. Incorrect.
Large image sizes typically impact the download phase of a waterfall chart rather than the 'Waiting (TTFB)' phase.
- D. Correct.
Poor DNS resolution performance can delay the establishment of the connection and subsequently increase the time spent in the 'Waiting (TTFB)' phase.
- E. Incorrect.
Client-side JavaScript execution issues occur after the response is received and affect rendering or functionality, not the 'Waiting (TTFB)' phase.