Infrastructure
· 17 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)
BDNSSECUnsigned (DNSSEC not deployed)REVIEW
BCAA RecordsNo CAA records (any CA may issue certificates)REVIEW
CReverse DNSAction0/4 IPs match cert SANREVIEW
CCrawlabilityActionrobots.txt present, sitemap with 0 URLsREVIEW
Search engines may not be able to parse the sitemap. Fix XML validation errors.
An unparseable sitemap is silently ignored by Google — the URLs it advertises are never queued for crawl.
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Google's sitemap parser is strict about XML validity. A single unescaped `&` or unclosed tag invalidates the whole file. Run your sitemap through a validator (Search Console's Sitemaps report flags it) and fix the offending entry. Most generators escape correctly; mistakes usually come from manually-written entries.
Source: sitemaps.org / Google Search Central
An empty sitemap provides no value. Add <url> entries for your pages.
An empty sitemap signals 'no content to index' to Google — actively harmful versus having no sitemap at all.
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Google compares URLs in the sitemap against URLs it has crawled. An empty sitemap on a site with thousands of pages signals abandonment. Either populate it correctly (most CMSes auto-generate) or delete the file and let Google crawl normally.
Source: Google Search Central / sitemaps.org
Add a 'Sitemap:' directive to robots.txt so search engines can discover your sitemap.
robots.txt omits Sitemap: directive — crawlers must fetch /sitemap.xml by convention; reliable but missing the explicit hint.
Source: sitemaps.org
<!doctype html><html lang="zh-CN"><head><meta charset="UTF-8"/><meta name="viewport" content="width=device-width,initial-scale=1.0"/><title>Nu11Cyber — 网络安全研究团队 | CTF Writeup & 漏洞复盘</title><meta name="description" content="{{DESCRIPTION}}"/><meta name="robots" content="index,follow"/><link rel="canonical" href="https://nu11cyber.com/"/><link rel="icon" type="image/png" sizes="32x32" href="/nu11-favicon.png"/><style>body{background:#070b12;color:#eef5ff;font-family:Inter,sans-serif;margin:0;padding:24px;line-height:1.8}pre{background:#0d1117;padding:16px;border-radius:8px;overflow-x:auto}code{font-size:0.9rem}h1,h2,h3{color:#25e6c8}a{color:#6ea8ff}img{max-width:100%}table{border-collapse:collapse;width:100%}th,td{border:1px solid rgba(255,255,255,0.14);padding:8px 12px;text-align:left}</style></head><body>{{CONTENT}}<script type="module" src="https://static.cloudflareinsights.com/beacon.min.js/v4bc70e2c01a94c73b74392e4234840661791215815920" integrity="sha512-L0ha0OXavK/8okipN9F8BtP84dg9DUhPERbBXzwI6dgTA55d2+yweo3pn5CSFYs45/r8md2+xvUPtTdvTNRfjA==" data-cf-beacon='{"version":"2024.11.0","token":"296296b3102f4f9e93a5fcb3c83317e0","r":1,"spa":2}' crossorigin="anonymous"></script>
</body></html>
BURL Variantswww/non-www, trailing slash, HTTP→HTTPSREVIEW
www / non-www
HTTP → HTTPS
HTTP version does not redirect to HTTPS
BTLS Certificate Expiry & Recommendations87 days until leaf cert expires — 3 issues to addressREVIEW
Certificate validity
Recommended actions
- Submit your domain to hstspreload.org to be added to the Chrome preload list
- 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
BOperational Status PageNo status page link detectedREVIEW
A+DNS Records2 A records, 17 ms lookupPASS
| A | 104.21.22.120, 172.67.204.204 |
| AAAA | 2606:4700:3033::ac43:cccc, 2606:4700:3033::6815:1678 |
| CNAME | — |
| NS | deborah.ns.cloudflare.com, zahir.ns.cloudflare.com |
| MX | — |
| TXT | — |
| CAA | Lookup not available with standard resolver |
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.
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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)
A+Subdomain TakeoverNo subdomain takeover risk detectedPASS
A+Multi-Resolver DNS SpeedMean 12ms across 3 resolvers (spread 8ms)PASS
A+Redirect ChainNo redirects — direct accessPASS
https://nu11cyber.com
371 ms · HTTP/1.1 FINAL
| # | URL | Status | Time | Protocol | Server |
|---|---|---|---|---|---|
| 1 | https://nu11cyber.com | 200 | 371 ms | HTTP/1.1 | cloudflare |
A+Domain Intelligencenu11cyber.com — via Tucows Domains Inc., 5 months old, hosted on CloudflarePASS
191 days
April 28, 2027
87 days
Issued by Let's Encrypt
5 months
Registered April 28, 2026
Not enabled
Protects against DNS spoofing
Cloudflare
ASN AS13335
104.21.22.120
Tucows Domains Inc.
Expiry timeline
Recommended actions
- Enable DNSSEC to protect visitors from DNS spoofing
- Newly registered domain — build backlinks and content to establish SEO trust
- Enable registrar lock (clientTransferProhibited) to block unauthorized domain transfers
Newly registered domains may face SEO trust challenges. Search engines generally give more authority to older domains. This is informational — not a problem to fix.
Informational: domain age. Newer domains may have lower trust signals in spam/security filters.
DNSSEC protects against DNS spoofing attacks. While not required, enabling DNSSEC adds an additional layer of security. Contact your DNS provider to enable it.
Without DNSSEC, an attacker who can poison your DNS can hijack your domain — and SSL certs alone don't stop them.
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DNSSEC adds cryptographic signatures to DNS records, preventing forged responses from poisoning resolver caches. Without it, an attacker who controls the network path can redirect your domain to a malicious server before any HTTPS handshake happens. Most modern registrars (Cloudflare, Google Domains, Route 53) enable it with one toggle.
Source: ICANN / RFC 4033
The domain can be transferred without an unlock step. Enable registrar lock (clientTransferProhibited) in your registrar's control panel to protect against unauthorized or accidental transfers.
Without registrar lock, an attacker who phishes your registrar credentials can transfer the domain in minutes — total brand hijack.
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Registrar lock (clientTransferProhibited, clientUpdateProhibited, clientDeleteProhibited) requires extra verification before any transfer/update/delete. Every major registrar offers it free. Combined with 2FA on your registrar account, it's the strongest defense against domain hijacking.
Source: ICANN / domain-security best practice