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https://epfl.ch

Infrastructure

· 9 checks — DNS, redirects, IPv6, crawlability, URL variants, and domain intelligence rolled into one auditable list.
SCORE
72
GRADE
C
FIX
3
REVIEW
1
PASS
4
INFO
1
Probed from Santa Clara, United States
301 Moved Permanently
Checks
9
4 PASS 1 REVIEW 3 FIX
D
Redirect Chain
Action
2 redirect(s), 1254 ms total
FIX
2 redirect(s), 1254 ms total
Warning::
2 redirects before reaching final URL
Each redirect adds latency. Try to minimize the chain to 1 hop.
Info::
WWW normalization redirect
Info::
Uses 302 (temporary) redirect
If permanent, use 301 instead.
Got: https://www.epfl.ch/
Warning::
Redirect overhead: 1254 ms total
Got: 1254 ms

https://epfl.ch

787 ms · HTTP/1.1

301

https://www.epfl.ch/

412 ms · HTTP/1.1

302

https://www.epfl.ch/fr/

55 ms · HTTP/1.1 FINAL

#URLStatusTimeProtocolServer
1https://epfl.ch301787 msHTTP/1.1Apache/2.4.63 (Unix)
2https://www.epfl.ch/302412 msHTTP/1.1cloudflare
3https://www.epfl.ch/fr/20055 msHTTP/1.1cloudflare

See the visual redirect chain in the HTTP Probe tab →

Each redirect adds latency. Try to minimize the chain to 1 hop.

Why this matters

Redirect chain — each hop adds latency; combine into one redirect where possible.

Source: Google Search Central / web.dev

If permanent, use 301 instead.

Why this matters

302 (Found) is for genuinely temporary redirects — if this redirect is permanent, switch to 301 to preserve SEO equity.

Learn more ▾

Search engines treat 302 as temporary, keeping the original URL indexed and not transferring full link equity to the destination. Use 301 (Moved Permanently) for permanent redirects (HTTP→HTTPS, www-vs-non-www, URL restructures).

Source: Google Search Central

F
IPv6 Readiness
Action
IPv6 records exist but unreachable
FIX
IPv6 records exist but unreachable
Warning::
IPv6 DNS records exist but server is not reachable
Having AAAA records but an unreachable server is worse than no AAAA — clients may experience delays before falling back to IPv4.
Got: 2001:620:618:1d3:7:80b2:d301:1b
Info::
IPv6 connection error
Got: dial tcp6 [2001:620:618:1d3:7:80b2:d301:1b]:443: connect: network is unreachable
IPv6 Misconfigured
AAAA Records 2001:620:618:1d3:7:80b2:d301:1b Connection UNREACHABLE

Having AAAA records but an unreachable server is worse than no AAAA — clients may experience delays before falling back to IPv4.

Why this matters

Advertising IPv6 (AAAA records) without a reachable server means IPv6-preferring clients silently fail every connection.

Learn more ▾

Modern browsers prefer IPv6 if AAAA exists (Happy Eyeballs algorithm). If the IPv6 server isn't reachable, browsers fall back to IPv4 — but with seconds of added latency per request. Either fix IPv6 reachability or remove the AAAA records.

Source: RFC 8305 (Happy Eyeballs)

D
CDN & Delivery
Action
No CDN detected
FIX
No CDN detected
Warning::
No CDN detected
A CDN can significantly improve load times for users around the world by caching content at edge nodes closer to them.
No CDN detected

Consider using a CDN to improve global delivery speed and reduce origin load.

B
TLS Certificate Expiry & Recommendations
209 days until leaf cert expires — 4 issues to address
REVIEW

Certificate validity

209
days left
0d 30d 60d 90d+

Recommended actions

  • Add includeSubDomains to the HSTS directive
  • Add the preload directive and submit to hstspreload.org once max-age + includeSubDomains are in place
  • Enable DNSSEC on your domain for DNS spoofing protection
  • Enable OCSP stapling on your TLS server to remove a CA roundtrip and protect user privacy
A
DNS Records
1 A records, 314 ms lookup
PASS
1 A records, 314 ms lookup
Info::
Resolves to 1 IPv4 address(es)
Got: 128.178.211.3
Info::
Single A record — no DNS redundancy
Multiple A records provide failover if one server goes down.
Info::
Has 1 IPv6 (AAAA) record(s)
Got: 2001:620:618:1d3:7:80b2:d301:1b
Info::
3 nameserver(s) configured
Got: stisun1.epfl.ch, stisun2.epfl.ch, scsnms.switch.ch
Info::
1 mail exchanger(s) configured
Info::
CAA records not checked
CAA record lookup requires a specialized DNS resolver. This check will be available in a future update.
Info::
SPF record present in TXT
Warning::
DNS resolution is slow (314 ms)
Slow DNS adds latency to every page load. Consider a faster DNS provider.
Got: 314 ms
A128.178.211.3
AAAA2001:620:618:1d3:7:80b2:d301:1b
CNAME—
NSstisun1.epfl.ch, stisun2.epfl.ch, scsnms.switch.ch
MX
50 epfl-ch.mail.protection.outlook.com
TXT
d365mktkey=3EwYyirHF4PZyfgrSxI3j0OXSuFxCpyFYiz69pxIai8x
SPF v=spf1 redirect=_spf.epfl.ch
d365mktkey=e4PFfOVs4CYe9A1zo362DbI92XypBMJ4jQBVU1Jnqxox
CAALookup not available with standard resolver
Resolved in 314 ms

Multiple A records provide failover if one server goes down.

Why this matters

Single A record means a single point of failure — if that IP goes down, your site is unreachable until DNS TTL expires.

Learn more ▾

Add multiple A records for round-robin failover, or use a managed DNS provider with health-checked failover (Route 53, Cloudflare, NS1). Short TTL (60-300s) lets clients recover faster on outages.

Source: SRE practice / DNS architecture

CAA record lookup requires a specialized DNS resolver. This check will be available in a future update.

Why this matters

Informational: CAA (Certification Authority Authorization) records weren't checked in this scan.

Slow DNS adds latency to every page load. Consider a faster DNS provider.

Why this matters

DNS resolution is slow — anycast DNS providers (Cloudflare, Route 53) typically resolve <50ms globally.

Source: DNS performance benchmarks

A+
Crawlability
robots.txt present, sitemap with 10789 URLs
PASS
robots.txt present, sitemap with 10789 URLs
Info::
robots.txt is present
Got: 0 bytes
Info::
sitemap.xml is present
Info::
sitemap.xml is valid XML
Info::
sitemap.xml contains 10789 entries
Info::
robots.txt does not reference a sitemap
Add a 'Sitemap:' directive to robots.txt so search engines can discover your sitemap.

Add a 'Sitemap:' directive to robots.txt so search engines can discover your sitemap.

Why this matters

robots.txt omits Sitemap: directive — crawlers must fetch /sitemap.xml by convention; reliable but missing the explicit hint.

Source: sitemaps.org

robots.txt 200 OK
Size 0 B Sitemaps referenced 0 User-agents Blocking No — crawling allowed
sitemap.xml 200 OK
Type URL Set URLs 10789 entries Valid XML Yes
Sample URLs:
A+
URL Variants
www/non-www, trailing slash, HTTP→HTTPS
PASS
www/non-www, trailing slash, HTTP→HTTPS
Info::
www/non-www redirect configured correctly (preferred: non-www)
Info::
HTTP correctly 301-redirects to HTTPS

www / non-www

302https://www.epfl.ch/
200https://epfl.ch/

Preferred variant: non-www

HTTP → HTTPS

301http://epfl.ch/ → https://epfl.ch/

Consistent

A
HTTP Probe Timing
Total 790 ms — DNS, TCP, TLS, TTFB, content transfer breakdown
PASS
DNS Lookup DNS Lookup — time to resolve the domain name to an IP address.
159 ms
TCP Connect TCP Connect — time to establish a TCP connection to the server.
156 ms
TLS Handshake TLS Handshake — time to complete the HTTPS encryption handshake.
314 ms
Time to First Byte Time to First Byte — how long the server takes to respond with the first byte of data.
790 ms
Total Time Total request time from DNS lookup through full response.
791 ms

Connection waterfall

DNS Lookup 159 ms TCP Connect 156 ms TLS Handshake 314 ms Server Processing 162 ms Content Transfer 0 ms
Domain Intelligence
Domain intelligence data not available
INFO
Domain intelligence data not available

RDAP and WHOIS lookup both failed

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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