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Infrastructure

· 9 checks — DNS, redirects, IPv6, crawlability, URL variants, and domain intelligence rolled into one auditable list.
SCORE
90
GRADE
A
FIX
0
REVIEW
3
PASS
6
INFO
0
Probed from Madrid, Spain
200 OK
Checks
9
6 PASS 3 REVIEW
B
DNS Records
4 A records, 33 ms lookup
REVIEW
4 A records, 33 ms lookup
Info::
Resolves to 4 IPv4 address(es)
Got: 143.204.55.31, 143.204.55.113, 143.204.55.86, 143.204.55.14
Info::
No IPv6 (AAAA) records
Warning::
CNAME record at zone apex
A CNAME at the zone apex can break MX and NS records. Use ALIAS/ANAME or A records instead.
Got: www-cloudfront-alias.coursera.org
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: 33 ms
Got: 33 ms
A143.204.55.31, 143.204.55.113, 143.204.55.86, 143.204.55.14
AAAA—
CNAMEwww-cloudfront-alias.coursera.org
NS—
MX—
TXT—
CAALookup not available with standard resolver
Resolved in 33 ms

A CNAME at the zone apex can break MX and NS records. Use ALIAS/ANAME or A records instead.

Why this matters

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.

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)

C
IPv6 Readiness
Action
No IPv6 support
REVIEW
No IPv6 support
Info::
No IPv6 (AAAA) records found
IPv6 support is increasingly important for global accessibility. About 40% of internet users have IPv6 connectivity.
No IPv6 Support
About 40% of internet users have IPv6. Consider adding AAAA records.

IPv6 support is increasingly important for global accessibility. About 40% of internet users have IPv6 connectivity.

Why this matters

No AAAA records — same impact as 'no IPv6 (AAAA) records'; IPv6-preferring clients pay extra latency falling back to IPv4.

Source: Google IPv6 stats

B
TLS Certificate Expiry & Recommendations
182 days until leaf cert expires — 3 issues to address
REVIEW

Certificate validity

182
days left
0d 30d 60d 90d+

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
A+
Redirect Chain
No redirects — direct access
PASS
No redirects — direct access
Info::
No redirects — direct access
Got: https://www.coursera.org

https://www.coursera.org

517 ms · HTTP/1.1 FINAL

#URLStatusTimeProtocolServer
1https://www.coursera.org200517 msHTTP/1.1envoy
A+
Crawlability
robots.txt present, sitemap with 18 URLs
PASS
robots.txt present, sitemap with 18 URLs
Info::
robots.txt is present
Got: 1291 bytes
Info::
sitemap.xml is present
Info::
sitemap.xml is valid XML
Info::
sitemap.xml contains 18 entries
Info::
Sitemap index with 18 child sitemaps
Info::
robots.txt references sitemap
robots.txt 200 OK
Size 1291 B Sitemaps referenced 1 User-agents PerplexityBot, OAI-SearchBot, ChatGPT-User, *, CCBot, GPTBot, MistralAI-User, Google-Extended, LinkedInBot, Twitterbot, meta-externalagent, ClaudeBot Blocking No — crawling allowed
User-agent: *
Allow: /api/utilities/v1/imageproxy
Disallow: /maestro/api/
Disallow: /api/
Disallow: /maestro/
Disallow: /ui/
Disallow: /signature/voucher/
Disallow: /account/
Disallow: /acclaimbadge/
Disallow: /voucher/
Disallow: /search
Disallow: /ent-website/
Disallow: /learn-perf/
Disallow: /specializations-perf/
Disallow: /professional-certificates-perf/
Disallow: /learn-noperf/
Disallow: /specializations-noperf/
Disallow: /professional-certificates-noperf/
Disallow: /business/xmlrpc.php
Disallow: /business/wp-content/uploads/ 
Disallow: /business/search
Disallow: /business/teams/search
Sitemap: https://www.coursera.org/sitemap.xml



User-agent: CCBot
Disallow: /lecture/

User-agent: GPTBot
Disallow: /lecture/

User-agent: ClaudeBot
Disallow: /lecture/

User-agent: MistralAI-User
Disallow: /lecture/

User-agent: Google-Extended
Disallow: /lecture/

User-agent: PerplexityBot
Disallow: /lecture/

User-agent: LinkedInBot
Allow: /account/accomplishments/

User-agent: Twitterbot
Allow: /account/accomplishments/

User-agent: meta-externalagent
Disallow: /

User-agent: OAI-SearchBot
Allow: /
Disallow: /programs/
Disallow: /account/
Disallow: /api/
Disallow: /search

User-agent: ChatGPT-User
Allow: /
Disallow: /programs/
Disallow: /account/
Disallow: /api/
Disallow: /search
sitemap.xml 200 OK
Type Sitemap Index URLs 18 entries Valid XML Yes
Child Sitemaps:
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: www)
Info::
HTTP correctly 301-redirects to HTTPS

www / non-www

200https://www.coursera.org/
301https://coursera.org/

Preferred variant: www

HTTP → HTTPS

301http://www.coursera.org/ → https://www.coursera.org/

Consistent

A+
Domain Intelligence
coursera.org — via GoDaddy.com, LLC, 14 years, 5 months old, hosted on AWS
PASS
coursera.org — via GoDaddy.com, LLC, 14 years, 5 months old, hosted on AWS
Info::
Domain registered until Jan 12, 2027 (9 months remaining)
Info::
DNSSEC is not enabled
DNSSEC protects against DNS spoofing attacks. While not required, enabling DNSSEC adds an additional layer of security. Contact your DNS provider to enable it.
Info::
Registrar: GoDaddy.com, LLC
Info::
Hosting: AWS
Got: AS16509
Domain expiry

148 days

January 12, 2027

SSL certificate

182 days

Issued by Amazon

Domain age

14 years, 5 months

Registered January 12, 2012

DNSSEC

Not enabled

Protects against DNS spoofing

Hosting

AWS

ASN AS16509

143.204.55.86

Registrar

GoDaddy.com, LLC

Lock status unknown 4 NS records
Expiry timeline
Today
+1 year
Domain expiry SSL expiry Danger zone (≤30 days)
Recommended actions
  • Enable DNSSEC to protect visitors from DNS spoofing
Registrar GoDaddy.com, LLC
Created January 12, 2012 (14 years, 5 months ago)
Expires January 12, 2027 (9 months)
Last Updated February 26, 2026
Name Servers ns-1481.awsdns-57.org, ns-1590.awsdns-06.co.uk, ns-258.awsdns-32.com, ns-688.awsdns-22.net
DNSSEC Not enabled
Hosting
IP Address 143.204.55.86
ASN AS16509 (AMAZON-02 - Amazon.com, Inc., US)
Provider AWS
Data source: rdap (0.7s)

DNSSEC protects against DNS spoofing attacks. While not required, enabling DNSSEC adds an additional layer of security. Contact your DNS provider to enable it.

Why this matters

Without DNSSEC, an attacker who can poison your DNS can hijack your domain — and SSL certs alone don't stop them.

Learn more ▾

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

A
HTTP Probe Timing
Total 557 ms — DNS, TCP, TLS, TTFB, content transfer breakdown
PASS
DNS Lookup DNS Lookup — time to resolve the domain name to an IP address.
56 ms
TCP Connect TCP Connect — time to establish a TCP connection to the server.
33 ms
TLS Handshake TLS Handshake — time to complete the HTTPS encryption handshake.
35 ms
Time to First Byte Time to First Byte — how long the server takes to respond with the first byte of data.
504 ms
Total Time Total request time from DNS lookup through full response.
558 ms

Connection waterfall

DNS Lookup 56 ms TCP Connect 33 ms TLS Handshake 35 ms Server Processing 380 ms Content Transfer 54 ms
A
CDN & Delivery
AWS CloudFront (Miss from cloudfront)
PASS
AWS CloudFront (Miss from cloudfront)
Info::
Site is served via AWS CloudFront CDN (edge: ZRH52-P1)
Got: x-amz-cf-id: gd7zThgKEhfw1kLUIGnm1SPsJb4gXabNcf2yDumWuVecf6yHKMoTrg==
Info::
CDN cache status: Miss from cloudfront
CDN Detected: AWS CloudFront
Provider AWS CloudFront Cache Status Miss from cloudfront Evidence x-amz-cf-id: gd7zThgKEhfw1kLUIGnm1SPsJb4gXabNcf2yDumWuVecf6yHKMoTrg==
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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