physicsclassroom.com

Readiness by lane

Green: physicsclassroom.com. Thin bar: Education & Online Learning peer median.

Priority fixes for physicsclassroom.com

Ordered by impact and by how common each practice is among peers.

1. Priority 1 · Harden

   HSTS kept for at least a year

   Observed: Strict-Transport-Security was sent with a max-age of 30 days, below the one-year benchmark.

   Why it matters: HSTS tells browsers to use HTTPS for your host on every later visit, which removes the window where a first HTTP request can be intercepted.

   What to do: Send Strict-Transport-Security on HTTPS responses. Start with a short max-age (for example 300 seconds), confirm every subdomain works over HTTPS, then raise it in steps to 31536000. Add includeSubDomains only when all subdomains are HTTPS. HSTS preload is optional and hard to undo; hstspreload.org itself does not recommend it by default.

   On Cloudflare: Enable HSTS under SSL/TLS > Edge Certificates > HTTP Strict Transport Security and raise max-age gradually.

   34% of Education & Online Learning peers do this. Limit: Read from the homepage response only; other pages or regions may send different headers.

   Guide: HTTPS and TLS Guide for Website Owners

2. Priority 2 · Enable

   XML sitemap discoverable

   Observed: No sitemap was listed in robots.txt or found at /sitemap.xml.

   What to do: Generate an XML sitemap of canonical URLs, reference it in robots.txt and submit it in Google Search Console.

   65% of Education & Online Learning peers do this.

   Guide: XML Sitemap Guide: Include Only URLs You Stand Behind

3. Priority 3 · Accelerate

   Modern image formats in use

   Observed: The homepage had 7 images and none used WebP or AVIF.

   What to do: Serve WebP or AVIF with a JPEG or PNG fallback, either through an image CDN or by generating both formats at build time.

   On Cloudflare: Cloudflare Polish can convert images to WebP.

   32% of Education & Online Learning peers do this.

   Guide: AVIF, WebP, JPEG, and PNG: Choose the Right Image Format

4. Priority 4 · Accelerate

   Offscreen images lazy-loaded

   Observed: The homepage had 7 images and none used loading="lazy".

   What to do: Add loading="lazy" to images below the fold. Do not lazy-load the main hero image, because that delays the largest visible element.

   52% of Education & Online Learning peers do this.

   Guide: Lazy Loading Without Broken Pages

What physicsclassroom.com already does well

Practices fewer than half of Education & Online Learning peers use.

• DMARC policy enforces quarantine or rejectDMARC policy p=quarantine.36% of peers
• Reachable over IPv6IPv6 address published.39% of peers
• No render-blocking scripts in <head>Head scripts load without blocking.42% of peers

What we saw

Homepage checked

https://www.physicsclassroom.com/

Homepage response

HTTP 200

TLS

TLSv1.3, HTTP/2

Certificate

Google Trust Services, 90-day validity, expiring 2026-11-29

CDN or edge

Cloudflare

DNS operators

Cloudflare

HSTS

max-age 30 days

DMARC policy

p=quarantine

Homepage HTML

723 KB, br

Images on homepage

7 (svg 7)

Limits: homepage only, one location, one moment. Header checks reflect the homepage response; other pages may differ.

Stack and providers

Seen in the homepage response, certificate and DNS. Provider pages compare how their customers configure the same checks.

All 31 checks

Select a gap for the method and fix. How each check works

Compare with other Education & Online Learning sites

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• seraj-uae.com62
• studia-online.pl62

Education & Online Learning readiness benchmark