1. General Results, most used to calculate the result A name "flow.maxcomm.com.br" is subdomain, public suffix is ".com.br", top-level-domain is ".br", top-level-domain-type is "country-code", Country is Brazil, tld-manager is "Comite Gestor da Internet no Brasil", num .br-domains preloaded: 2925 (complete: 231048) A Good: All ip addresses are public addresses Warning: Only one ip address found: flow.maxcomm.com.br has only one ip address. Warning: No ipv6 address found. Ipv6 is the future with a lot of new features. So every domain name should have an ipv6 address. See https://en.wikipedia.org/wiki/IPv6: flow.maxcomm.com.br has no ipv6 address. 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. X Fatal error: Nameserver doesn't support TCP connection: dns2.maxcomm.com.br / 177.129.248.24: Timeout Info: Checking the ip addresses of that domain name not exact one certificate found. So it's impossible to check if that domain requires Server Name Indication (SNI).: Domain flow.maxcomm.com.br, 1 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.flow.maxcomm.com.br 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:: 2 Root-climbing DNS Queries required to find all IPv4- and IPv6-Addresses of 2 Name Servers. A Info:: 2 Queries complete, 2 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.dns1.maxcomm.com.br (177.129.248.23, 2804:db8:100::23), dns2.maxcomm.com.br (177.129.248.24, 2804:db8:100::24) A Good (1 - 3.0):: An average of 1.0 queries per domain name server required to find all ip addresses of all name servers. A Info:: 2 different Name Servers found: dns1.maxcomm.com.br, dns2.maxcomm.com.br, 2 Name Servers included in Delegation: dns1.maxcomm.com.br, dns2.maxcomm.com.br, 2 Name Servers included in 2 Zone definitions: dns1.maxcomm.com.br, dns2.maxcomm.com.br, 1 Name Servers listed in SOA.Primary: dns1.maxcomm.com.br. A Good: Only one SOA.Primary Name Server found.: dns1.maxcomm.com.br. A Good: SOA.Primary Name Server included in the delegation set.: dns1.maxcomm.com.br. 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: No Name Server IPv6 address found. IPv6 is the future, so your name servers should be visible via IPv6.: 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: com.br 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: maxcomm.com.br Warning: All Name Servers from the same Country / IP location.: 2 Name Servers, 1 Countries: BR A Info: Ipv4-Subnet-list: 2 Name Servers, 1 different subnets (first Byte): 177., 1 different subnets (first two Bytes): 177.129., 1 different subnets (first three Bytes): 177.129.248. X Fatal: All Name Server IPv4 addresses from the same subnet. Check https://www.iana.org/help/nameserver-requirements to learn some basics about name server configurations. If you manage these name servers, fix it. If it's your provider, change your provider.: A Good: Nameserver supports TCP connections: 1 good Nameserver A Good: Nameserver supports Echo Capitalization: 1 good Nameserver X Nameserver Timeout checking Echo Capitalization: dns2.maxcomm.com.br / 177.129.248.24 A Good: Nameserver supports EDNS with max. 512 Byte Udp payload, message is smaller: 1 good Nameserver X Nameserver Timeout checking EDNS512: dns2.maxcomm.com.br / 177.129.248.24 A Good: Nameserver has passed 10 EDNS-Checks (OP100, FLAGS, V1, V1OP100, V1FLAGS, DNSSEC, V1DNSSEC, NSID, COOKIE, CLIENTSUBNET): 1 good Nameserver Nameserver doesn't pass all EDNS-Checks: dns1.maxcomm.com.br: 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: dns2.maxcomm.com.br / 177.129.248.24: OP100: fatal timeout. FLAGS: fatal timeout. V1: fatal timeout. V1OP100: fatal timeout. V1FLAGS: fatal timeout. DNSSEC: fatal timeout. V1DNSSEC: fatal timeout. NSID: fatal timeout. COOKIE: fatal timeout. CLIENTSUBNET: fatal timeout. 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://flow.maxcomm.com.br/.well-known/acme-challenge/check-your-website-dot-server-daten-dot-de 177.129.248.16 Fatal: Check of /.well-known/acme-challenge/random-filename has a timeout. 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. 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: 442200 milliseconds, 442.200 seconds