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https://cas.cz

Infrastructure

· 9 checks — DNS, redirects, IPv6, crawlability, URL variants, and domain intelligence rolled into one auditable list.
SCORE
81
GRADE
B
FIX
2
REVIEW
3
PASS
4
INFO
0
Probed from Santa Clara, United States
301 Moved Permanently
Checks
9
4 PASS 3 REVIEW 2 FIX
D
Redirect Chain
Action
2 redirect(s), 3081 ms total
FIX
2 redirect(s), 3081 ms total
Warning::
2 redirects before reaching final URL
Each redirect adds latency. Try to minimize the chain to 1 hop.
Info::
WWW normalization redirect
Warning::
Redirect overhead: 3081 ms total
Got: 3081 ms
Info::
Cross-domain redirect detected

https://cas.cz

812 ms · HTTP/1.1

301

https://www.avcr.cz/

1000 ms · HTTP/1.1

301

https://www.avcr.cz/cs/

1270 ms · HTTP/1.1 FINAL

#URLStatusTimeProtocolServer
1https://cas.cz301812 msHTTP/1.1Apache/2.4.37 (CentOS Stream) OpenSSL/1.1.1k
2https://www.avcr.cz/3011000 msHTTP/1.1OpenCms/11.0.x
3https://www.avcr.cz/cs/2001270 msHTTP/1.1OpenCms/11.0.x

See the visual redirect chain in the HTTP Probe tab →

Each redirect adds latency. Try to minimize the chain to 1 hop.

Why this matters

Redirect chain — each hop adds latency; combine into one redirect where possible.

Source: Google Search Central / web.dev

D
CDN & Delivery
Action
No CDN detected
FIX
No CDN detected
Warning::
No CDN detected
A CDN can significantly improve load times for users around the world by caching content at edge nodes closer to them.
No CDN detected

Consider using a CDN to improve global delivery speed and reduce origin load.

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
HTTP Probe Timing
Total 954 ms — DNS, TCP, TLS, TTFB, content transfer breakdown
REVIEW
DNS Lookup DNS Lookup — time to resolve the domain name to an IP address.
338 ms
TCP Connect TCP Connect — time to establish a TCP connection to the server.
153 ms
TLS Handshake TLS Handshake — time to complete the HTTPS encryption handshake.
310 ms
Time to First Byte Time to First Byte — how long the server takes to respond with the first byte of data.
954 ms
Total Time Total request time from DNS lookup through full response.
955 ms

Connection waterfall

DNS Lookup 338 ms TCP Connect 153 ms TLS Handshake 310 ms Server Processing 153 ms Content Transfer 0 ms
B
TLS Certificate Expiry & Recommendations
176 days until leaf cert expires — 2 issues to address
REVIEW

Certificate validity

176
days left
0d 30d 60d 90d+

Recommended actions

  • Enable HSTS: Strict-Transport-Security: max-age=31536000; includeSubDomains
  • Enable OCSP stapling on your TLS server to remove a CA roundtrip and protect user privacy
A+
DNS Records
1 A records, 161 ms lookup
PASS
1 A records, 161 ms lookup
Info::
Resolves to 1 IPv4 address(es)
Got: 147.231.163.240
Info::
Single A record — no DNS redundancy
Multiple A records provide failover if one server goes down.
Info::
No IPv6 (AAAA) records
Info::
3 nameserver(s) configured
Got: nsa.ces.net, visla.utia.cas.cz, academy.cas.cz
Info::
1 mail exchanger(s) configured
Info::
CAA records not checked
CAA record lookup requires a specialized DNS resolver. This check will be available in a future update.
Info::
SPF record present in TXT
Info::
DNS resolution time: 161 ms
Got: 161 ms
A147.231.163.240
AAAA—
CNAME—
NSnsa.ces.net, visla.utia.cas.cz, academy.cas.cz
MX
10 cas-cz.mail.protection.outlook.com
TXT
MS=ms15273704
PS-1DE9E9D695DD8C6BCB650BF86B69107D861F5A07
google-site-verification=vUDwTSfcIbP-SZlB4YtOHK9HptYiG6lYnU2bDgAbgqs
SPF v=spf1 ip4:147.231.58.32 ip4:147.231.163.131 include:spf.protection.outlook.com ...
eZQUjdgG4Qz1lrWWUR2cbrxQzAfv6E8v5ZR6ERf7euQqDDSdKQQQ0MMjQLs5ERt6cGUN8tGMy8fMmLeo...
CAALookup not available with standard resolver
Resolved in 161 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.

A
Crawlability
robots.txt present, no sitemap
PASS
robots.txt present, no sitemap
Info::
robots.txt is present
Got: 1616 bytes
Info::
No sitemap.xml found
A sitemap helps search engines discover and index your pages more efficiently.
Info::
robots.txt references sitemap

A sitemap helps search engines discover and index your pages more efficiently.

Why this matters

No sitemap.xml — Google relies on crawl-graph discovery alone, slowing indexing of deep or fresh URLs.

Learn more ▾

A sitemap accelerates Google's discovery of new and updated content. Most CMSes auto-generate one; static-site frameworks need a build-step plugin. Reference it from robots.txt and submit in Search Console to confirm Google can fetch it.

Source: sitemaps.org / Google Search Central

robots.txt 200 OK
Size 1616 B Sitemaps referenced 1 User-agents * Blocking No — crawling allowed
Sitemap: https://www.avcr.cz/sitemap.xml

User-agent: *
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/organizer/
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/finis-austriae/
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/czechoslovexit/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/from-sumava-to-tatry/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/phenomenal-president-masaryk/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/collective-violence-during-the-first-republic/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/an-island-of-democracy/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/values/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/borders-and-customs/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/landscape-transformations-and-protection/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/science-and-progress/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/the-leaven-of-the-republic/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/people-on-an-ice-block/ 
Disallow: /cs/pro-verejnost/vystavy/republika-ceskoslovenska-1918-1939/the-republic-in-the-uncertain-world/
Disallow: /cs/forms/
Disallow: /cs/forms/OAV-stream/
Disallow: /cs/forms/soudni-znalectvi/  
Disallow: /cs/forms/jmena/
Disallow: /cs/pro-verejnost/casopisy/nove-cislo/
Disallow: /LeviGyr/
Disallow: /avex/
sitemap.xml No sitemap found

No sitemap found

Adding a sitemap helps search engines discover your pages.

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.cas.cz/
200https://cas.cz/

Preferred variant: non-www

HTTP → HTTPS

301http://cas.cz/ → https://www.avcr.cz/

Consistent

A+
Domain Intelligence
cas.cz — via REG-GRANSY, 29 years, 11 months old, hosted on CESNET2, CZ
PASS
cas.cz — via REG-GRANSY, 29 years, 11 months old, hosted on CESNET2, CZ
Info::
Domain registered until Oct 28, 2034 (8 years, 7 months remaining)
Info::
DNSSEC is enabled
Info::
Registrar: REG-GRANSY
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: CESNET2, CZ
Got: AS2852
Domain expiry

3057 days

October 28, 2034

SSL certificate

176 days

Issued by Hellenic Academic and Research Institutions CA

Domain age

29 years, 11 months

Registered October 6, 1996

DNSSEC

Enabled

Protects against DNS spoofing

Hosting

CESNET2, CZ

ASN AS2852

147.231.163.240

Registrar

REG-GRANSY

Unlocked 3 NS records
Expiry timeline
Today
+1 year
Domain expiry SSL expiry Danger zone (≤30 days)
Recommended actions
  • Enable registrar lock (clientTransferProhibited) to block unauthorized domain transfers
Registrar REG-GRANSY
Created October 6, 1996 (29 years, 11 months ago)
Expires October 28, 2034 (8 years, 7 months)
Last Updated May 15, 2025
Name Servers academy.cas.cz, nsa.ces.net, visla.utia.cas.cz
DNSSEC Enabled
Hosting
IP Address 147.231.163.240
ASN AS2852 (CESNET2, CZ)
Provider CESNET2, CZ
Data source: rdap (1.0s)

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

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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