300-445 Question 193
Single answerA company has received user complaints about slow web application performance. As a network engineer, you collect browser waterfall data to diagnose the issue. The waterfall reveals the following patterns: a long DNS lookup time, short connection time, and significant delays in the 'waiting' (TTFB) phase. Based on this data, what is the most likely cause of the performance issue?
- A
High DNS resolution time due to misconfigured DNS servers
- B
Network congestion causing delays in packet delivery
- C
Server-side processing delays leading to high Time to First Byte (TTFB)
- D
Browser rendering issues causing slow page load times
Show answer and explanation
Correct answer: C
Explanation
The browser waterfall data provides critical insights into where delays occur in the web application loading process. Long DNS lookup times or network congestion would typically lead to delays in connection or transfer phases, while browser rendering issues affect the load phase. In this scenario, the observed delay in the 'waiting' (TTFB) phase strongly suggests that server-side processing is the root cause of the performance issue. Identifying patterns in the waterfall data is key to diagnosing web application performance problems.
- A. Incorrect.
While the DNS lookup time is long, the connection time is short, indicating that DNS resolution may not be the primary cause of the issue. Additionally, this does not explain the delay in the 'waiting' (TTFB) phase.
- B. Incorrect.
Network congestion could cause delays in packet delivery, but this would typically manifest as long connection times or slow data transfer phases, not specifically in the 'waiting' (TTFB) phase.
- C. Correct.
The significant delay in the 'waiting' (TTFB) phase strongly indicates server-side processing delays. This is the most likely cause, as it aligns with the observed waterfall data.
- D. Incorrect.
Browser rendering issues would typically occur after the 'waiting' (TTFB) phase has completed and would not cause delays specifically in the TTFB phase.