1. General Results, most used to calculate the result A name "docuware.mertens.ag" is subdomain, public suffix is ".ag", top-level-domain is ".ag", top-level-domain-type is "country-code", Country is Antigua and Barbuda, tld-manager is "UHSA School of Medicine", num .ag-domains preloaded: 125 (complete: 228216) A Good: No asked Authoritative Name Server had a timeout A DNS: "Name Error" means: No www-dns-entry defined. This isn't a problem HSTS-Preload-Status: unknown. Domain never included in the Preload-list. Check https://hstspreload.org/ to learn some basics about the Google-Preload-List. 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.docuware.mertens.ag 2. Header-Checks U No https result with http status 2** or 4** (standard-check) found, no header checked. 3. DNS- and NameServer - Checks A Info:: 4 Root-climbing DNS Queries required to find all IPv4- and IPv6-Addresses of 3 Name Servers. A Info:: 4 Queries complete, 4 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.ns.second-ns.com (213.239.204.242, 2a01:4f8:0:a101::b:1), ns1.your-server.de (213.133.100.102, 2a01:4f8:0:1::5ddc:1), ns3.second-ns.de (193.47.99.4, 2001:67c:192c::add:b3) A Good (1 - 3.0):: An average of 1.3 queries per domain name server required to find all ip addresses of all name servers. A Info:: 3 different Name Servers found: ns.second-ns.com, ns1.your-server.de, ns3.second-ns.de, 3 Name Servers included in Delegation: ns.second-ns.com, ns1.your-server.de, ns3.second-ns.de, 3 Name Servers included in 1 Zone definitions: ns.second-ns.com, ns1.your-server.de, ns3.second-ns.de, 1 Name Servers listed in SOA.Primary: ns1.your-server.de. A Good: Only one SOA.Primary Name Server found.: ns1.your-server.de. A Good: SOA.Primary Name Server included in the delegation set.: ns1.your-server.de. 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 Info: Ipv4-Subnet-list: 3 Name Servers, 2 different subnets (first Byte): 193., 213., 3 different subnets (first two Bytes): 193.47., 213.133., 213.239., 3 different subnets (first three Bytes): 193.47.99., 213.133.100., 213.239.204. A Good: Name Server IPv4-addresses from different subnet found: A Info: IPv6-Subnet-list: 3 Name Servers with IPv6, 2 different subnets (first block): 2001:, 2a01:, 2 different subnets (first two blocks): 2001:067c:, 2a01:04f8:, 2 different subnets (first three blocks): 2001:067c:192c:, 2a01:04f8:0000:, 3 different subnets (first four blocks): 2001:067c:192c:0000:, 2a01:04f8:0000:0001:, 2a01:04f8:0000:a101: A Good: Name Server IPv6 addresses from different subnets found. A Good: Nameserver supports TCP connections: 6 good Nameserver A Good: Nameserver supports Echo Capitalization: 6 good Nameserver 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.your-server.de: OP100: no result. FLAGS: no result. V1: no result. V1OP100: no result. V1FLAGS: no result. DNSSEC: no result. V1DNSSEC: no result. NSID: no result. COOKIE: no result. CLIENTSUBNET: no result. Nameserver doesn't pass all EDNS-Checks: ns1.your-server.de: OP100: no result. FLAGS: no result. V1: no result. V1OP100: no result. V1FLAGS: no result. DNSSEC: no result. V1DNSSEC: no result. NSID: no result. COOKIE: no result. CLIENTSUBNET: no result. 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 Info: Creating a Letsencrypt certificate with that domain name isn't possible. To create a certificate you need a registered, worldwide unique domain name. The domain name ends with a public suffix, that's good (not Grade Z). But the domain isn't registered. If you want a certificate with that domain name, you have to proof that you are the domain owner. Trouble creating a certificate? Use https://community.letsencrypt.org/ to ask. 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: 63010 milliseconds, 63.010 seconds