SEO Engine Performance & Tuning 3 — Questions and Answers
Question 1: Which technique bundles multiple CSS background images into a single file to reduce HTTP requests?
- Image compression
- CSS sprites (Correct answer)
- WebP conversion
- Lazy loading
Correct answer: CSS sprites
CSS sprites combine multiple images into one file, using background-position to display specific portions, reducing HTTP requests.
Question 2: What does the 'defer' attribute on a script tag do?
- Prevents the script from ever running
- Loads and executes the script before HTML parsing completes
- Downloads the script in parallel but executes after HTML parsing (Correct answer)
- Caches the script indefinitely
Correct answer: Downloads the script in parallel but executes after HTML parsing
The defer attribute downloads the script without blocking HTML parsing and executes it after the document is fully parsed.
Question 3: Which Google tool measures real-world Core Web Vitals data from actual Chrome users visiting a site?
- Google PageSpeed Insights Lab Data
- Chrome User Experience Report (CrUX) (Correct answer)
- Lighthouse CI
- Search Console Coverage Report
Correct answer: Chrome User Experience Report (CrUX)
CrUX aggregates real-world performance data from opted-in Chrome users and powers the 'field data' shown in PageSpeed Insights.
Question 4: A CDN (Content Delivery Network) improves SEO performance primarily by:
- Adding structured data automatically
- Serving assets from edge nodes geographically closer to users (Correct answer)
- Blocking bad bots more efficiently
- Generating XML sitemaps
Correct answer: Serving assets from edge nodes geographically closer to users
CDNs cache and serve static assets from edge servers near users, reducing latency and improving load times and TTFB.
Question 5: Which resource hint tells the browser to establish a connection to a third-party origin in advance, including DNS, TCP, and TLS?
- dns-prefetch
- preload
- preconnect (Correct answer)
- prefetch
Correct answer: preconnect
Preconnect performs the full connection handshake (DNS + TCP + TLS) in advance, unlike dns-prefetch which only resolves DNS.
Question 6: Render-blocking resources negatively impact which Core Web Vital MOST directly?
- Cumulative Layout Shift (CLS)
- Largest Contentful Paint (LCP) (Correct answer)
- Interaction to Next Paint (INP)
- Time to Interactive (TTI)
Correct answer: Largest Contentful Paint (LCP)
Render-blocking CSS and JS delay the browser from rendering content, directly pushing back the LCP element paint time.
Question 7: What is the recommended maximum LCP (Largest Contentful Paint) threshold for a 'Good' score according to Google?
- 1.0 seconds
- 2.5 seconds (Correct answer)
- 4.0 seconds
- 5.0 seconds
Correct answer: 2.5 seconds
Google defines LCP as 'Good' when it occurs within 2.5 seconds; 2.5–4.0s is 'Needs Improvement' and above 4.0s is 'Poor'.
SEO Engine Performance & Tuning 3
Which technique bundles multiple CSS background images into a single file to reduce HTTP requests?