Infrastructure
· 9 checks — DNS, redirects, IPv6, crawlability, URL variants, and domain intelligence rolled into one auditable list.FIPv6 ReadinessActionIPv6 records exist but unreachableFIX
Having AAAA records but an unreachable server is worse than no AAAA — clients may experience delays before falling back to IPv4.
Advertising IPv6 (AAAA records) without a reachable server means IPv6-preferring clients silently fail every connection.
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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)
DTLS Certificate Expiry & RecommendationsAction11 days until leaf cert expires — 6 issues to addressFIX
Certificate validity
Recommended actions
- Renew certificate — 11 days remaining
- Prefer TLS 1.3 — TLS 1.2 is acceptable but TLS 1.3 removes RSA key exchange and improves latency
- 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
CDNS RecordsAction1 A records, 323 ms lookupREVIEW
| A | 151.101.250.133 |
| AAAA | 2a04:4e42:3b::645 |
| CNAME | pantheon-systems.map.fastly.net |
| NS | — |
| MX | — |
| TXT | — |
| CAA | Lookup not available with standard resolver |
Multiple A records provide failover if one server goes down.
Single A record means a single point of failure — if that IP goes down, your site is unreachable until DNS TTL expires.
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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
A CNAME at the zone apex can break MX and NS records. Use ALIAS/ANAME or A records instead.
CNAME at the apex (example.com) breaks every other apex record (MX, TXT, NS) — DNS-protocol violation per RFC 1034.
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RFC 1034 forbids CNAME alongside other records at the same name. Some DNS providers offer ALIAS / ANAME / flattened-CNAME records that work around this — use those instead. Otherwise apex-level CNAME breaks email (no MX), domain ownership verification (no TXT), and more.
Source: RFC 1034
CAA record lookup requires a specialized DNS resolver. This check will be available in a future update.
Informational: CAA (Certification Authority Authorization) records weren't checked in this scan.
SPF helps prevent email spoofing. Add a TXT record starting with 'v=spf1'.
Without SPF, receiving servers can't validate sending IPs — your domain is easier to spoof in phishing.
Learn more ▾ ▴
SPF complements DMARC. Both should be published. SPF records list authorized sending IPs (e.g., `v=spf1 include:_spf.google.com ~all` for Google Workspace). After publishing, verify in Google Postmaster Tools or mxtoolbox.
Source: RFC 7208 (SPF)
Slow DNS adds latency to every page load. Consider a faster DNS provider.
DNS resolution is slow — anycast DNS providers (Cloudflare, Route 53) typically resolve <50ms globally.
Source: DNS performance benchmarks
A+Redirect ChainNo redirects — direct accessPASS
https://www.stanford.edu
324 ms · HTTP/1.1 FINAL
| # | URL | Status | Time | Protocol | Server |
|---|---|---|---|---|---|
| 1 | https://www.stanford.edu | 200 | 324 ms | HTTP/1.1 | nginx |
A+Crawlabilityrobots.txt present, sitemap with 5 URLsPASS
User-agent: *
Disallow: /wp-admin/
Allow: /wp-admin/admin-ajax.php
Sitemap: https://www.stanford.edu/wp-sitemap.xml
A+URL Variantswww/non-www, trailing slash, HTTP→HTTPSPASS
www / non-www
Preferred variant: www
HTTP → HTTPS
Consistent
A+Domain Intelligencestanford.edu — 41 years, 1 months oldPASS
750 days
July 31, 2028
11 days
Issued by Certainly
41 years, 1 months
Registered October 4, 1985
Status unknown
Protects against DNS spoofing
Unknown
2607:f6d0:0:925a::ab43:d7c8
Registrar unknown
Expiry timeline
Recommended actions
- Renew the TLS certificate or verify auto-renewal is working