1. General Results, most used to calculate the result A name "optom1.ru" is domain, public suffix is ".ru", top-level-domain is ".ru", top-level-domain-type is "country-code", Country is Russian Federation (the), tld-manager is "Coordination Center for TLD RU", num .ru-domains preloaded: 2472 (complete: 221801) A Good: All ip addresses are public addresses A Good: Minimal 2 ip addresses per domain name found: optom1.ru has 2 different ip addresses (authoritative). A Good: Minimal 2 ip addresses per domain name found: www.optom1.ru has 2 different ip addresses (authoritative). A Good: Ipv4 and Ipv6 addresses per domain name found: optom1.ru has 1 ipv4, 1 ipv6 addresses A Good: Ipv4 and Ipv6 addresses per domain name found: www.optom1.ru has 1 ipv4, 1 ipv6 addresses A Good: No asked Authoritative Name Server had a timeout HSTS-Preload-Status: unknown. Domain never included in the Preload-list. Check https://hstspreload.org/ to learn some basics about the Google-Preload-List. A Good: All urls with http status 200/404 have a complete Content-Type header (MediaType / MediaSubType + correct charset) B https://optom1.ru/ 95.181.226.15 Missing HSTS-Header B https://www.optom1.ru/ 95.181.226.15 Missing HSTS-Header http://optom1.ru/ 95.181.226.15 PHPSESSID=6n7gin1i181r6aajdvfidbc5jc; path=/; HttpOnly Fatal: Cookie sent via http. Never send Cookies / Session-Cookies via http. If a user uses an insecure WLan and if the same cookie is used to managed the authenticated session, it's possible to hack that user. Same with HttpOnly - without https that's only decorative. http://optom1.ru/ 95.181.226.15 opt1_basket_id=46527998; expires=Sun, 25-Jun-2023 05:34:23 GMT; Max-Age=2592000; path=/ Fatal: Cookie sent via http. Never send Cookies / Session-Cookies via http. If a user uses an insecure WLan and if the same cookie is used to managed the authenticated session, it's possible to hack that user. Same with HttpOnly - without https that's only decorative. http://www.optom1.ru/ 95.181.226.15 PHPSESSID=6irj1d8rdjucsuh8snfl16sj81; path=/; HttpOnly Fatal: Cookie sent via http. Never send Cookies / Session-Cookies via http. If a user uses an insecure WLan and if the same cookie is used to managed the authenticated session, it's possible to hack that user. Same with HttpOnly - without https that's only decorative. http://www.optom1.ru/ 95.181.226.15 opt1_basket_id=46528001; expires=Sun, 25-Jun-2023 05:34:25 GMT; Max-Age=2592000; path=/ Fatal: Cookie sent via http. Never send Cookies / Session-Cookies via http. If a user uses an insecure WLan and if the same cookie is used to managed the authenticated session, it's possible to hack that user. Same with HttpOnly - without https that's only decorative. http://optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15 PHPSESSID=m2c5l2gbcacpi5ghc65eu85sst; path=/; HttpOnly Fatal: Cookie sent via http. Never send Cookies / Session-Cookies via http. If a user uses an insecure WLan and if the same cookie is used to managed the authenticated session, it's possible to hack that user. Same with HttpOnly - without https that's only decorative. http://optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15 opt1_basket_id=46528029; expires=Sun, 25-Jun-2023 05:34:42 GMT; Max-Age=2592000; path=/ Fatal: Cookie sent via http. Never send Cookies / Session-Cookies via http. If a user uses an insecure WLan and if the same cookie is used to managed the authenticated session, it's possible to hack that user. Same with HttpOnly - without https that's only decorative. http://www.optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15 PHPSESSID=t43fqp097ill7dkih2etb0sbhi; path=/; HttpOnly Fatal: Cookie sent via http. Never send Cookies / Session-Cookies via http. If a user uses an insecure WLan and if the same cookie is used to managed the authenticated session, it's possible to hack that user. Same with HttpOnly - without https that's only decorative. http://www.optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15 opt1_basket_id=46528030; expires=Sun, 25-Jun-2023 05:34:43 GMT; Max-Age=2592000; path=/ Fatal: Cookie sent via http. Never send Cookies / Session-Cookies via http. If a user uses an insecure WLan and if the same cookie is used to managed the authenticated session, it's possible to hack that user. Same with HttpOnly - without https that's only decorative. B https://optom1.ru/ 95.181.226.15 PHPSESSID=4eh8ie206n27tf2ctk3clp70nv; path=/; HttpOnly Cookie sent via https, but not marked as secure B https://optom1.ru/ 95.181.226.15 opt1_basket_id=46528004; expires=Sun, 25-Jun-2023 05:34:28 GMT; Max-Age=2592000; path=/ Cookie sent via https, but not marked as secure B https://www.optom1.ru/ 95.181.226.15 PHPSESSID=oiehm5bl8gkv7s546025nh01iq; path=/; HttpOnly Cookie sent via https, but not marked as secure B https://www.optom1.ru/ 95.181.226.15 opt1_basket_id=46528019; expires=Sun, 25-Jun-2023 05:34:35 GMT; Max-Age=2592000; path=/ Cookie sent via https, but not marked as secure B https://95.181.226.15/ 95.181.226.15 PHPSESSID=21if558snsfa28490vaoguombq; path=/; HttpOnly Cookie sent via https, but not marked as secure B https://95.181.226.15/ 95.181.226.15 opt1_basket_id=46528031; expires=Sun, 25-Jun-2023 05:34:45 GMT; Max-Age=2592000; path=/ Cookie sent via https, but not marked as secure B http://optom1.ru/ 95.181.226.15 PHPSESSID=6n7gin1i181r6aajdvfidbc5jc; path=/; HttpOnly Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B http://optom1.ru/ 95.181.226.15 opt1_basket_id=46527998; expires=Sun, 25-Jun-2023 05:34:23 GMT; Max-Age=2592000; path=/ Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B http://www.optom1.ru/ 95.181.226.15 PHPSESSID=6irj1d8rdjucsuh8snfl16sj81; path=/; HttpOnly Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B http://www.optom1.ru/ 95.181.226.15 opt1_basket_id=46528001; expires=Sun, 25-Jun-2023 05:34:25 GMT; Max-Age=2592000; path=/ Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B https://optom1.ru/ 95.181.226.15 PHPSESSID=4eh8ie206n27tf2ctk3clp70nv; path=/; HttpOnly Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B https://optom1.ru/ 95.181.226.15 opt1_basket_id=46528004; expires=Sun, 25-Jun-2023 05:34:28 GMT; Max-Age=2592000; path=/ Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B https://www.optom1.ru/ 95.181.226.15 PHPSESSID=oiehm5bl8gkv7s546025nh01iq; path=/; HttpOnly Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B https://www.optom1.ru/ 95.181.226.15 opt1_basket_id=46528019; expires=Sun, 25-Jun-2023 05:34:35 GMT; Max-Age=2592000; path=/ Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B http://optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15 PHPSESSID=m2c5l2gbcacpi5ghc65eu85sst; path=/; HttpOnly Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B http://optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15 opt1_basket_id=46528029; expires=Sun, 25-Jun-2023 05:34:42 GMT; Max-Age=2592000; path=/ Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B http://www.optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15 PHPSESSID=t43fqp097ill7dkih2etb0sbhi; path=/; HttpOnly Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B http://www.optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15 opt1_basket_id=46528030; expires=Sun, 25-Jun-2023 05:34:43 GMT; Max-Age=2592000; path=/ Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B https://95.181.226.15/ 95.181.226.15 PHPSESSID=21if558snsfa28490vaoguombq; path=/; HttpOnly Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. B https://95.181.226.15/ 95.181.226.15 opt1_basket_id=46528031; expires=Sun, 25-Jun-2023 05:34:45 GMT; Max-Age=2592000; path=/ Cookie without a SameSite-Attribute. Possible values are: Strict/Lax/None. Cookie may not work as expected, if "None" is wanted, but browsers use "Lax" as default value. C Error - no preferred version www or non-www. Select one version as preferred version, then add a redirect https + not-preferred version to https + preferred version. Perhaps in your port 443 vHost something like "RewriteEngine on" + "RewriteCond %{SERVER_NAME} = example.com" + "ReWriteRule ^ https://www.example.com%{REQUEST_URI} [END,QSA,R=permanent]" (three rows, without the "). That should create a redirect https + example.com ⇒ https + www.example.com. Or switch both values to use the non-www version as your preferred version. C Error - more then one version with Http-Status 200. After all redirects, all users (and search engines) should see the same https url: Non-www or www, but not both with http status 200. H Fatal error: http result with http-status 200, no encryption. Add a redirect http ⇒ https, so every connection is secure. Perhaps in your port 80 vHost something like "RewriteEngine on" + "RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,QSA,R=permanent]" (two rows, without the "). Don't add this in your port 443 vHost, that would create a loop. K http://optom1.ru/ 95.181.226.15, Status 200 http://optom1.ru/ 2a03:c980:e5:1a::, Status -2 Configuration problem - different ip addresses with different status K http://www.optom1.ru/ 95.181.226.15, Status 200 http://www.optom1.ru/ 2a03:c980:e5:1a::, Status -2 Configuration problem - different ip addresses with different status K https://optom1.ru/ 95.181.226.15, Status 200 https://optom1.ru/ 2a03:c980:e5:1a::, Status -2 Configuration problem - different ip addresses with different status K https://www.optom1.ru/ 95.181.226.15, Status 200 https://www.optom1.ru/ 2a03:c980:e5:1a::, Status -2 Configuration problem - different ip addresses with different status K http://optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15, Status 404 http://optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 2a03:c980:e5:1a::, Status -2 Configuration problem - different ip addresses with different status K http://www.optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15, Status 404 http://www.optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 2a03:c980:e5:1a::, Status -2 Configuration problem - different ip addresses with different status N https://95.181.226.15/ 95.181.226.15 Error - Certificate isn't trusted, RemoteCertificateNameMismatch V http://optom1.ru/ 2a03:c980:e5:1a:: Connect failure - perhaps firewall V http://www.optom1.ru/ 2a03:c980:e5:1a:: Connect failure - perhaps firewall V https://optom1.ru/ 2a03:c980:e5:1a:: Connect failure - perhaps firewall V https://www.optom1.ru/ 2a03:c980:e5:1a:: Connect failure - perhaps firewall V http://optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 2a03:c980:e5:1a:: Connect failure - perhaps firewall V http://www.optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 2a03:c980:e5:1a:: Connect failure - perhaps firewall V https://[2a03:c980:00e5:001a:0000:0000:0000:0000]/ 2a03:c980:e5:1a:: Connect failure - perhaps firewall X Fatal error: Nameserver doesn't support TCP connection: b.dns.ripn.net: Timeout A Good: More then one ip address per domain name found, checking all ip addresses the same http status and the same certificate found: Domain optom1.ru, 2 ip addresses. A Good: More then one ip address per domain name found, checking all ip addresses the same http status and the same certificate found: Domain www.optom1.ru, 2 ip addresses. B No _mta-sts TXT record found (mta-sts: Mail Transfer Agent Strict Transport Security - see RFC 8461). Read the result of server-daten.de (Url-Checks, Comments, Connections and DomainServiceRecords) to see a complete definition. Domainname: _mta-sts.optom1.ru 2. Header-Checks (alpha, started 2022-10-23, may be buggy / incomplete) A optom1.ru 95.181.226.15 X-Content-Type-Options Ok: Header without syntax errors found: nosniff A X-Frame-Options Ok: Header without syntax errors found: SAMEORIGIN B Info: Header is deprecated. May not longer work in modern browsers. SAMEORIGIN. Better solution: Use a Content-Security-Policy Header with a frame-ancestors directive. DENY - use 'none', SAMEORIGIN - use 'self'. If you want to allow some domains to frame your page, add these urls. A www.optom1.ru 95.181.226.15 X-Content-Type-Options Ok: Header without syntax errors found: nosniff A X-Frame-Options Ok: Header without syntax errors found: SAMEORIGIN B Info: Header is deprecated. May not longer work in modern browsers. SAMEORIGIN. Better solution: Use a Content-Security-Policy Header with a frame-ancestors directive. DENY - use 'none', SAMEORIGIN - use 'self'. If you want to allow some domains to frame your page, add these urls. F optom1.ru 95.181.226.15 Content-Security-Policy Critical: Missing Header: F optom1.ru 95.181.226.15 Referrer-Policy Critical: Missing Header: F optom1.ru 95.181.226.15 Permissions-Policy Critical: Missing Header: F www.optom1.ru 95.181.226.15 Content-Security-Policy Critical: Missing Header: F www.optom1.ru 95.181.226.15 Referrer-Policy Critical: Missing Header: F www.optom1.ru 95.181.226.15 Permissions-Policy Critical: Missing Header: 3. DNS- and NameServer - Checks A Info:: 5 Root-climbing DNS Queries required to find all IPv4- and IPv6-Addresses of 2 Name Servers. A Info:: 5 Queries complete, 5 with IPv6, 0 with IPv4. A Good: All DNS Queries done via IPv6. A Good: Some ip addresses of name servers found with the minimum of two DNS Queries. One to find the TLD-Zone, one to ask the TLD-Zone.ns1.ihc.ru (185.71.65.216, 2a03:c980:beef:6002:46:254:23:52, 46.254.23.52), ns2.ihc.ru (190.115.26.198, 91.121.54.18) A Good (1 - 3.0):: An average of 2.5 queries per domain name server required to find all ip addresses of all name servers. A Info:: 2 different Name Servers found: ns1.ihc.ru, ns2.ihc.ru, 2 Name Servers included in Delegation: ns1.ihc.RU, ns2.ihc.RU, 2 Name Servers included in 1 Zone definitions: ns1.ihc.ru, ns2.ihc.ru, 1 Name Servers listed in SOA.Primary: ns1.ihc.ru. A Good: Only one SOA.Primary Name Server found.: ns1.ihc.ru. A Good: SOA.Primary Name Server included in the delegation set.: ns1.ihc.ru. A Good: Consistency between delegation and zone. The set of NS records served by the authoritative name servers must match those proposed for the delegation in the parent zone. Ordered list of name servers: ns1.ihc.ru, ns2.ihc.ru A Good: All Name Server Domain Names have a Public Suffix. A Good: All Name Server Domain Names ending with a Public Suffix have minimal one IPv4- or IPv6 address. A Good: All Name Server ip addresses are public. A Good: Minimal 2 different name servers (public suffix and public ip address) found: 2 different Name Servers found Warning: All Name Servers have the same Top Level Domain / Public Suffix. If there is a problem with that Top Level Domain, your domain may be affected. Better: Use Name Servers with different top level domains.: 2 Name Servers, 1 Top Level Domain: ru Warning: All Name Servers have the same domain name. If there is a problem with that domain name (or with the name servers of that domain name), your domain may be affected. Better: Use Name Servers with different domain names / different top level domains.: Only one domain name used: ihc.ru A Good: Name servers with different Country locations found: 2 Name Servers, 3 Countries: BZ, FR, RU A Info: Ipv4-Subnet-list: 4 Name Servers, 4 different subnets (first Byte): 185., 190., 46., 91., 4 different subnets (first two Bytes): 185.71., 190.115., 46.254., 91.121., 4 different subnets (first three Bytes): 185.71.65., 190.115.26., 46.254.23., 91.121.54. A Excellent: Every Name Server IPv4-address starts with an unique Byte. A Info: IPv6-Subnet-list: 2 Name Servers with IPv6, 2 different subnets (first block): 2001:, 2a03:, 2 different subnets (first two blocks): 2001:41d0:, 2a03:c980:, 2 different subnets (first three blocks): 2001:41d0:1008:, 2a03:c980:beef:, 2 different subnets (first four blocks): 2001:41d0:1008:2c3b:, 2a03:c980:beef:6002: A Excellent: Every Name Server IPv6-address starts with an unique Hex-block A Good: Nameserver supports TCP connections: 6 good Nameserver A Good: Nameserver supports Echo Capitalization: 6 good Nameserver X Nameserver Timeout checking Echo Capitalization: b.dns.ripn.net A Good: Nameserver supports EDNS with max. 512 Byte Udp payload, message is smaller: 6 good Nameserver Nameserver doesn't pass all EDNS-Checks: ns1.ihc.ru / 185.71.65.216: OP100: ok. FLAGS: ok. V1: ok. V1OP100: ok. V1FLAGS: ok. DNSSEC: ok. V1DNSSEC: ok. NSID: ok (ns-stormwall.ihc-ru.net). COOKIE: ok. CLIENTSUBNET: ok. A Good: All SOA have the same Serial Number Warning: No CAA entry with issue/issuewild found, every CAA can create a certificate. Read https://en.wikipedia.org/wiki/DNS_Certification_Authority_Authorization to learn some basics about the idea of CAA. Your name server must support such an entry. Not all dns providers support CAA entries. 4. Content- and Performance-critical Checks http://optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 2a03:c980:e5:1a:: Fatal: Check of /.well-known/acme-challenge/random-filename is blocked, http connection error. Creating a Letsencrypt certificate via http-01 challenge can't work. You need a running webserver (http) and an open port 80. If it's a home server + ipv4, perhaps a correct port forwarding port 80 extern ⇒ working port intern is required. Port 80 / http can redirect to another domain port 80 or port 443, but not other ports. If it's a home server, perhaps your ISP blocks port 80. Then you may use the dns-01 challenge. Trouble creating a certificate? Use https://community.letsencrypt.org/ to ask. http://www.optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 2a03:c980:e5:1a:: Fatal: Check of /.well-known/acme-challenge/random-filename is blocked, http connection error. Creating a Letsencrypt certificate via http-01 challenge can't work. You need a running webserver (http) and an open port 80. If it's a home server + ipv4, perhaps a correct port forwarding port 80 extern ⇒ working port intern is required. Port 80 / http can redirect to another domain port 80 or port 443, but not other ports. If it's a home server, perhaps your ISP blocks port 80. Then you may use the dns-01 challenge. Trouble creating a certificate? Use https://community.letsencrypt.org/ to ask. http://optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 2a03:c980:e5:1a::, Status -2 http://optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15, Status 404 Fatal: Check of /.well-known/acme-challenge/random-filename has different answers checking ipv6 / ipv4. Ipv6 doesn't have the expected result http status 404 - Not Found. Creating a Letsencrypt certificate via http-01 validation may not work. Checking the validation file in /.well-known/acme-challenge Letsencrypt prefers ipv6. Two options: Remove your ipv6 / AAAA DNS entry or (better) fix your ipv6, so your webserver handles ipv6 correct. Perhaps add "Listen [::]:80". Don't use <VirtualHost ip-address:80>, switch to <VirtualHost *:80>. If you use IIS, check your bindings. Don't select a single ip address. Use this tool to check your raw ipv6 address. Add your domain name in the "Hostname" - field. Trouble creating a certificate? Use https://community.letsencrypt.org/ to ask. http://www.optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 2a03:c980:e5:1a::, Status -2 http://www.optom1.ru/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 95.181.226.15, Status 404 Fatal: Check of /.well-known/acme-challenge/random-filename has different answers checking ipv6 / ipv4. Ipv6 doesn't have the expected result http status 404 - Not Found. Creating a Letsencrypt certificate via http-01 validation may not work. Checking the validation file in /.well-known/acme-challenge Letsencrypt prefers ipv6. Two options: Remove your ipv6 / AAAA DNS entry or (better) fix your ipv6, so your webserver handles ipv6 correct. Perhaps add "Listen [::]:80". Don't use <VirtualHost ip-address:80>, switch to <VirtualHost *:80>. If you use IIS, check your bindings. Don't select a single ip address. Use this tool to check your raw ipv6 address. Add your domain name in the "Hostname" - field. Trouble creating a certificate? Use https://community.letsencrypt.org/ to ask. A Good: Every https result with status 200 supports GZip. https://optom1.ru/ 95.181.226.15 Warning: Https result with status 200 found, Html-Content is too big. Should be max. 110 %. May contain inline CSS / JavaScript, too much comments or white space. Re-used ressources - create files with a long Cache-Control max-age header. Remove comments and white space. https://www.optom1.ru/ 95.181.226.15 Warning: Https result with status 200 found, Html-Content is too big. Should be max. 110 %. May contain inline CSS / JavaScript, too much comments or white space. Re-used ressources - create files with a long Cache-Control max-age header. Remove comments and white space. https://95.181.226.15/ 95.181.226.15 Warning: Https result with status 200 found, Html-Content is too big. Should be max. 110 %. May contain inline CSS / JavaScript, too much comments or white space. Re-used ressources - create files with a long Cache-Control max-age header. Remove comments and white space. A Good: Every https connection via port 443 supports the http/2 protocol via ALPN. A Info: No img element found, no alt attribute checked A Good: Domainname is not on the "Specially Designated Nationals And Blocked Persons List" (SDN). That's an US-list of individuals and companies owned or controlled by, or acting for or on behalf of, targeted countries. It also lists individuals, groups, and entities, such as terrorists and narcotics traffickers designated under programs that are not country-specific. Collectively, such individuals and companies are called "Specially Designated Nationals" or "SDNs." Their assets are blocked and U.S. persons are generally prohibited from dealing with them. So if a domain name is on that list, it's impossible to create a Letsencrypt certificate with that domain name. Check the list manual - https://www.treasury.gov/resource-center/sanctions/sdn-list/pages/default.aspx A Duration: 366506 milliseconds, 366.506 seconds