NAME

check_soa - Check nameservers for a domain

SYNOPSIS

check_soa [-d] [-n] [-t] [-v] domain [nameserver]

DESCRIPTION

check_soa builds a list of nameservers for the zone which contains the specified domain name. The program queries each nameserver for the relevant SOA record and reports the zone serial number.

Error reports are generated for nameservers which reply with incorrect, non-authoritative or outdated information.

domain: Fully qualified domain name to be tested. Domains within ip6.arpa or in-addr.arpa namespaces may be specified using the appropriate IP address or prefix notation.
nameserver: Optional name or list of IP addresses of specific nameserver to be tested. Addresses are used in the sequence they appear in the argument list.

SOA query packets are sent to the nameservers as rapidly as the underlying hardware will allow. The program waits for a response only when it is needed for analysis. Execution time is determined by the slowest nameserver.

This perldoc(1) documentation page is displayed if the domain argument is omitted.

The program is based on the check_soa idea described by Albitz and Liu.

OPTIONS

-d: Turn on resolver diagnostics.
-n: Report negative cache TTL.
-t: Ignore UDP datagram truncation.
-v: Verbose output including address records for each nameserver.

EXAMPLES

check_soa example.com: Query all nameservers for the specified domain.
check_soa example.com ns.icann.org: Query specific nameserver as above.
check_soa 192.168.99.0: Query nameservers for specified in-addr.arpa subdomain.
check_soa 2001:DB8::8:800:200C:417A: Query nameservers for specified ip6.arpa subdomain.
check_soa 2001:DB8:0:CD30::/60: As above, for IPv6 address prefix of specified length.

BUGS

The program can become confused by zones which originate, or appear to originate, from more than one primary server.

The timeout code exploits the 4 argument form of select() function. This is not guaranteed to work in non-Unix environments.

COPYRIGHT

This program is free software; you may use or redistribute it under the same terms as Perl itself.

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