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https://pubmed.ncbi.nlm.nih.gov

Infrastructure

· 9 checks — DNS, redirects, IPv6, crawlability, URL variants, and domain intelligence rolled into one auditable list.
SCORE
97
GRADE
A+
FIX
0
REVIEW
2
PASS
7
INFO
0
Probed from Madrid, Spain
200 OK
Checks
9
7 PASS 2 REVIEW
B
TLS Certificate Expiry & Recommendations
157 days until leaf cert expires — 2 issues to address
REVIEW

Certificate validity

157
days left
0d 30d 60d 90d+

Recommended actions

  • Submit your domain to hstspreload.org to be added to the Chrome preload list
  • Enable OCSP stapling on your TLS server to remove a CA roundtrip and protect user privacy
B
CDN & Delivery
Google Cloud CDN
REVIEW
Google Cloud CDN
Info::
Site is served via Google Cloud CDN CDN
Got: via: 1.1 google
CDN Detected: Google Cloud CDN
Provider Google Cloud CDN Evidence via: 1.1 google
A
DNS Records
1 A records, 112 ms lookup
PASS
1 A records, 112 ms lookup
Info::
Resolves to 1 IPv4 address(es)
Got: 34.107.134.59
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: 2600:1901:0:c831::
Info::
No NS records found
Info::
No MX records — email not configured via DNS
Info::
CAA records not checked
CAA record lookup requires a specialized DNS resolver. This check will be available in a future update.
Info::
No SPF record found in TXT records
SPF helps prevent email spoofing. Add a TXT record starting with 'v=spf1'.
Info::
DNS resolution time: 112 ms
Got: 112 ms
A34.107.134.59
AAAA2600:1901:0:c831::
CNAME
NS
MX
TXT
CAALookup not available with standard resolver
Resolved in 112 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.

SPF helps prevent email spoofing. Add a TXT record starting with 'v=spf1'.

Why this matters

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)

A+
Redirect Chain
No redirects — direct access
PASS
No redirects — direct access
Info::
No redirects — direct access
Got: https://pubmed.ncbi.nlm.nih.gov

https://pubmed.ncbi.nlm.nih.gov

204 ms · HTTP/1.1 FINAL

#URLStatusTimeProtocolServer
1https://pubmed.ncbi.nlm.nih.gov200204 msHTTP/1.1nginx
A+
IPv6 Readiness
IPv6 reachable (17 ms)
PASS
IPv6 reachable (17 ms)
Info::
IPv6 is configured and reachable at 2600:1901:0:c831::
Got: 17 ms connect
IPv6 Ready
AAAA Records 2600:1901:0:c831:: Connection Reachable (17 ms)
A+
Crawlability
robots.txt present, sitemap with 0 URLs
PASS
robots.txt present, sitemap with 0 URLs
Info::
robots.txt is present
Got: 1341 bytes
Info::
sitemap.xml is present
Info::
sitemap.xml is valid XML
Info::
sitemap.xml contains 0 entries
Info::
Sitemap index with 0 child sitemaps
Info::
robots.txt references sitemap
robots.txt 200 OK
Size 1341 B Sitemaps referenced 1 User-agents * Blocking No — crawling allowed
User-agent: *
Crawl-delay: 1
Disallow: /api
Disallow: /rss
Disallow: /advanced/adv-suggestions/
Disallow: /terms/
Disallow: /addToHistory/
Disallow: /deleteHistory/
Disallow: /downloadHistory/
Disallow: /deleteHistoryRecord/
Disallow: /historyCacheExists/
Disallow: /*/references/
Disallow: /*/citations/
Disallow: /*/export/
Disallow: /*/citedby/
Disallow: /*/similar/
Disallow: /*/adj-nav/
Disallow: /ajax/
Disallow: /clipboard/
Disallow: /clipboard-next-page/
Disallow: /health/
Disallow: /deep-health-abstract/
Disallow: /deep-health-search/
Disallow: /deep-health-auth/
Disallow: /error/400/
Disallow: /error/403/
Disallow: /error/404/
Disallow: /error/500/
Disallow: /results-export-ids/
Disallow: /results-export-search-data/
Disallow: /results-export-email-by-search-data/
Disallow: /results-export-search-by-year/
Disallow: /send-email/
Disallow: /list-existing-collections/
Disallow: /add-to-existing-collection/
Disallow: /create-and-add-to-new-collection/
Disallow: /toggle-favorites-collection/
Disallow: /list-bibliography-delegates/
Disallow: /add-to-bibliography/
Disallow: /create-saved-search/
Disallow: /create-rss-feed-url/
Disallow: /searches/
Disallow: /collections/
Disallow: /more/
Disallow: /suggestions/
Disallow: /try-search-term/
Disallow: /rss-feed/

Sitemap: https://pubmed.ncbi.nlm.nih.gov/sitemap?p=index.xml

sitemap.xml 200 OK
Type Sitemap Index URLs 0 entries Valid XML Yes
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

301https://www.pubmed.ncbi.nlm.nih.gov/
200https://pubmed.ncbi.nlm.nih.gov/

Preferred variant: non-www

HTTP → HTTPS

301http://pubmed.ncbi.nlm.nih.gov/ https://pubmed.ncbi.nlm.nih.gov:443/

Consistent

A+
Domain Intelligence
nih.gov — via get.gov, 28 years, 11 months old, hosted on NIH-NET - National Institutes of Health, US
PASS
nih.gov — via get.gov, 28 years, 11 months old, hosted on NIH-NET - National Institutes of Health, US
Info::
Domain registered until Aug 22, 2026 (4 months remaining)
Info::
DNSSEC is enabled
Info::
Registrar: get.gov
Warning::
Registrar lock is NOT enabled
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.
Info::
Hosting: NIH-NET - National Institutes of Health, US
Got: AS3527
Domain expiry

39 days

August 22, 2026

SSL certificate

157 days

Issued by GoDaddy.com, Inc.

Domain age

28 years, 11 months

Registered October 2, 1997

DNSSEC

Enabled

Protects against DNS spoofing

Hosting

NIH-NET - National Institutes of Health, US

ASN AS3527

156.40.212.210

Registrar

get.gov

Unlocked 3 NS records
Expiry timeline
Today
+1 year
Domain expiry SSL expiry Danger zone (≤30 days)
Recommended actions
  • Renew the domain or enable auto-renewal to prevent accidental expiry
  • Enable registrar lock (clientTransferProhibited) to block unauthorized domain transfers
Registrar get.gov
Created October 2, 1997 (28 years, 11 months ago)
Expires August 22, 2026 (4 months)
Last Updated March 4, 2026
Name Servers ns.nih.gov, ns2.nih.gov, ns3.nih.gov
DNSSEC Enabled
Registrant REDACTED FOR PRIVACY
Hosting
IP Address 156.40.212.210
ASN AS3527 (NIH-NET - National Institutes of Health, US)
Provider NIH-NET - National Institutes of Health, US
Data source: rdap (0.7s)

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.

Why this matters

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

A+
HTTP Probe Timing
Total 232 ms — DNS, TCP, TLS, TTFB, content transfer breakdown
PASS
DNS Lookup DNS Lookup — time to resolve the domain name to an IP address.
17 ms
TCP Connect TCP Connect — time to establish a TCP connection to the server.
17 ms
TLS Handshake TLS Handshake — time to complete the HTTPS encryption handshake.
20 ms
Time to First Byte Time to First Byte — how long the server takes to respond with the first byte of data.
223 ms
Total Time Total request time from DNS lookup through full response.
232 ms

Connection waterfall

DNS Lookup 17 ms TCP Connect 17 ms TLS Handshake 20 ms Server Processing 169 ms Content Transfer 10 ms
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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