Domain name DNS test
czech version | english version
This service allows you to perform the test of authoritative nameservers for a specific domain name, its settings, status, availability etc. It also shows you many useful information about the domain name and its zone (A, NS and MX records etc.).
NOTICE: This service is still under development and the list of tests and their behavior can be changed at any time. In case of any questions or trouble, please contact me using an e-mail address mentioned at the end of this page. Thank you.
To perform a test, write down the domain name in to the following form.
List of performed tests on domain
The following table shows a full list of tests that are performed on a particular domain name and its autoritative name servers (DNS servers). The second column tells you the correct result of the test. Some of these test can have more than one negative result with different consequences.
| List of performed tests on domain | |
| test name | expected correct result |
| DNS servers response | All name servers for this domain name respond to DNS queries |
| zone serial numbers | All name servers return the same serial number in SOA record |
| authoritativity of name servers for the domain | All name servers are authoritative for this domain name |
| attendance of required glue records at parent server | There are all required glue records on parent server |
| glue records and A records in zone matching | Glue records match with A records in the zone |
| attendance of NS records in the zone | Zone of the domain name contains NS records |
| NS records and authoritative name servers matching | NS records from the zone match NS records from parent server |
| recursive queries | None of name servers offer recursive services |
| public zone transfer (AXFR) | None of name servers offer zone transfer (AXFR) for this domain name |
| name servers on public IP | All name servers are on public IP addresses |
| recommended number of name servers | The domain has recommended 2-7 name servers |
| TTL values in NS records on parent server | TTL values of NS records at parent server matches |
| TTL values in NS records in the zone | TTL values of NS records in the zone matches |
| reverse records of name servers | Reverse records of DNS servers matches with their IP addresses |
| name servers in different autonomous systems (AS) | DNS servers are at least in 2 different autonomous systems (AS) thus their availability is not dependent on one network |
| name servers in different subnets | DNS servers are at least in 2 different subnets |
| different IPv4 addresses of name servers | DNS servers have different IP addresses |
| server from SOA MNAME as NS record | DNS server from SOA MNAME entry is listed as NS record in the zone |
| MNAME entry check | SOA MNAME entry is syntactically valid |
| similar MNAME in SOA from all name servers | All DNS servers return the name MNAME value in SOA record |
| RNAME entry check | SOA RNAME entry is syntactically valid |
| recommended format of serial number (YYYYMMDDnn) | The serial number of the zone has recommended syntax YYYYMMDDnn |
| REFRESH value check | SOA REFRESH value is within recommended range 20m-12h |
| RETRY value check | SOA RETRY value is less than REFRESH value and is at least 15m |
| EXPIRE value check | SOA EXPIRE value is within recommended range 14d-31d and is more than REFRESH+RETRY |
| MINIMUM value check | SOA MINIMUM value is within recommended range 1-3h |
| contact WWW server | Connection to WWW server using HTTP protocol is all right |
| HTTP response code | Response from WWW server is correct, no error detected |
| Mailserver software detection | |
| AAAA records presence | |
| TTL values in A records | TTL values in A records are equal |
| TTL values in AAAA records | TTL values in AAAA records are equal |
| Reverse records of WWW server | Reverse records matches with their IP addresses |
| Number of MX records | The domain does not contain any MX record or at least 2 MX records |
| Syntax check of MX records | All MX records are syntactically correct |
| Resolve MX records to IP address | All MX records can be correctly resolved to IP address |
| MX records duplicity | MX records are not duplicated |
| TTL values of MX records | TTL values of MX records are equal |
| Reverse reverse records of MX records | Reverse records match with their IP addresses |
| Connection with primary mailserver | Connection with primary mailserver is corrent and the server accepts e-mails for this domain |
| Connection to other mailservers | Connections to all other mailservers are correct and accept e-mails for this domain |
| Mailserver software detection | Software of mailserver has been detected |
| Detection of available extensions (ESMTP) | Mailserver offer ESMTP extensions |
| Greylisting | |
| AAAA records presence | All mailservers have IPv6 address (AAAA records) |
| SPF records presence | |
| Open relay mailservers | None of mailserver is open relay, thus they accepts e-mails only for domains that are configured for. |
| Mail servers in DNSBL blacklists | None of mailservers is listed in any DNSBL servers thus they are not the source of spam |
| SRV SIP records presence | |
| Syntax check of SRV records | All SRV records are syntactically correct |
| Resolve SIP servers from SRV records to IP addresses | All domain names from SRV SIP records can be resolved to IP address |
| SRV records duplicity | SRV records are not duplicate |
| TTL values check for SRV records | TTL values for SRV records are equal |
| Reverse records for SIP servers | Reverse records match their IP addresses |
| AAAA records presence for SIP servers | All SIP servers have IPv6 addresses (AAAA records) |
| DNSKEY record presence | The domain has DNSKEY record, thus it is secured by DNSSEC technology |
(c) Petr Šťastný 2010, e-mail: 