Infrastructure
· 9 checks — DNS, redirects, IPv6, crawlability, URL variants, and domain intelligence rolled into one auditable list.DURL VariantsActionwww/non-www, trailing slash, HTTP→HTTPSFIX
www / non-www
Inconsistent — duplicate content risk
HTTP → HTTPS
HTTP version does not redirect to HTTPS
DCDN & DeliveryActionNo CDN detectedFIX
Consider using a CDN to improve global delivery speed and reduce origin load.
CIPv6 ReadinessActionNo IPv6 supportREVIEW
IPv6 support is increasingly important for global accessibility. About 40% of internet users have IPv6 connectivity.
No AAAA records — same impact as 'no IPv6 (AAAA) records'; IPv6-preferring clients pay extra latency falling back to IPv4.
Source: Google IPv6 stats
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.
Learn more ▾ ▴
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.
Learn more ▾ ▴
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" />
<link rel="icon" type="image/x-icon" href="/favicon.ico" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta name="description" content="51LA - 领先的数据统计服务商" />
<title>51LA - 领先的数据统计服务商</title>
<script type="module" crossorigin src="/js/index-8kzxuVEg.js"></script>
<link rel="stylesheet" crossorigin href="/css/index-CfDB1C6o.css">
</head>
<body>
<div id="app"></div>
</body>
</html>
BTLS Certificate Expiry & Recommendations177 days until leaf cert expires — 3 issues to addressREVIEW
Certificate validity
Recommended actions
- Enable HSTS: Strict-Transport-Security: max-age=31536000; includeSubDomains
- 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
ADNS Records1 A records, 151 ms lookupPASS
| A | 43.159.107.113 |
| AAAA | — |
| CNAME | 51.la.eo.dnse3.com |
| NS | ns4.dnsv4.com, ns3.dnsv4.com |
| MX | — |
| TXT | globalsign-domain-verification=uzZcAGlo0n87On_AxmTUYLEPxmE1td0HAregMvl1oH globalsign-domain-verification=vaW1PC9eB6hPFDT2Iy169g56PB9ft8NLjYKSLcfPrC SPF v=spf1 include:spf.mail.qq.com ~all |
| 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.
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
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.
Learn more ▾ ▴
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.
A+Redirect ChainNo redirects — direct accessPASS
https://51.la
43 ms · HTTP/1.1 FINAL
| # | URL | Status | Time | Protocol | Server |
|---|---|---|---|---|---|
| 1 | https://51.la | 200 | 43 ms | HTTP/1.1 | nginx/1.20.1 |
A+Domain Intelligence51.la — via Key-Systems GmbH, 21 years, 6 months old, hosted on ACE-AS-AP ACE, SGPASS
519 days
January 17, 2028
177 days
Issued by PKI(Chongqing) Limited
21 years, 6 months
Registered January 17, 2005
Status unknown
Protects against DNS spoofing
ACE-AS-AP ACE, SG
ASN AS139341
43.159.107.113
Key-Systems GmbH
Expiry timeline
Recommended actions
- Enable registrar lock (clientTransferProhibited) to block unauthorized domain transfers
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.
Learn more ▾ ▴
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