300-445 Question 199
Single answerA company has received complaints from users about slow webpage loading times for their web application. You are tasked with diagnosing the issue using browser waterfall data. Upon analyzing the browser waterfall, you notice that the 'Time to First Byte' (TTFB) is significantly higher than expected. What could be the most likely cause of this issue?
- A
High server processing time causing delays in generating the response
- B
Large image files being loaded on the webpage
- C
Client-side JavaScript taking too long to execute
- D
DNS resolution delay for the web application domain
Show answer and explanation
Correct answer: A
Explanation
Time to First Byte (TTFB) measures the time it takes for the browser to receive the first byte of data from the server after making the request. A high TTFB typically indicates server-side issues, such as high processing time or resource contention, as the server is taking too long to generate and send the response. Other factors like large image files or JavaScript execution affect the total page load time but not the TTFB.
- A. Correct.
High server processing time can directly lead to an increased Time to First Byte (TTFB), as it delays the server's ability to send the initial response to the client.
- B. Incorrect.
Large image files being loaded affect the overall page loading time but do not specifically influence the Time to First Byte (TTFB), which measures the time it takes for the first byte of data to reach the client.
- C. Incorrect.
Client-side JavaScript execution occurs after the initial data is received from the server, so it does not impact the Time to First Byte (TTFB).
- D. Incorrect.
DNS resolution delay can impact the time before the request reaches the server, but it is not a direct factor in increasing the Time to First Byte (TTFB), which begins after the server starts processing the request.