dnsviz-probe - Man Page

issue diagnostic DNS queries


dnsviz probe [ options ] [ domain_name... ]


Perform a series of diagnostic queries of specified names to either recursive (default) or authoritative DNS servers, the results of which are serialized into JSON format.  Its output is used to assess the health of DNS deployments, using, e.g., dnsviz-grok(1) and dnsviz-graph(1).

Domain names to be processed may be passed either as command-line arguments or in a file (using the -f option).  When the -r option is used, then the domain names can simply be implied using the diagnostic query input.

Domain names are extracted from the diagnostic query input in conjunction with -r only when -f is not used and no domain names are supplied on the command line.  If the -f option is used, then names may not be specified on the command line.

The domain names passed as input are fully-qualified domain names, such as example.com, www.example.com, _443._tcp.example.com,, or 8.b.d.  Because it is implied that specified domain names are fully qualified, no trailing dot is necessary.


-f,  --names-file filename

Read names from a file (one name per line), instead of from command line.

If this option is used, then names may not be specified on the command line.

-d,  --debug level

Set debug level to a value from 0 to 3, with increasing verbosity.  The default is "2" (informational-level output).

-r,  --input-file filename

Read diagnostic query input from the specified file, instead of querying servers.  Specify "-" to read from standard input.

-t,  --threads threads

Issue diagnostic queries for different names in parallel using the specified number of threads.  The default is to execute diagnostic queries of names serially.

-4,  --ipv4

Use IPv4 only.

-6,  --ipv6

Use IPv6 only.

-b,  --source-ip address

Use the specified source IPv4 or IPv6 address for queries, rather than detecting it.

This option can be used more than once to supply both an IPv4 and an IPv6 address.

The use of this option is sometimes necessary when using a dual-homed machine, and it is desirable to use the non-default interface for queries.

-u,  --looking-glass-url url

Issue queries through the DNS looking glass at the specified URL (HTTP(S) or SSH).  The queries will appear to come from the looking glass rather than from the local machine.


Issue DNS queries from www.example.com using the cgi script dnsviz-lg.cgi:


Same, but use HTTP Basic authentication:


Issue DNS queries from host.example.com on which DNSViz is also installed.


Note that a looking glass that uses https is only supported when using python version 2.7.9 or greater.

-k,  --insecure

Do not verify the server-side TLS certificate for a HTTPS-based DNS looking glass that was specified using -u.

-a,  --ancestor ancestor

Issue diagnostic queries of each domain name through the specified ancestor.  The default for recursive mode is "." (i.e., issue queries all the way to the root).   The default for authoritative mode (i.e., with -A) is the domain name itself.

-R,  --rr-types type[,type...]

Issue diagnostic queries for only the specified type(s) (e.g., A, AAAA).  The default is to pick query types based on the nature of the name (e.g., the number of labels, whether it is a subdomain of .arpa, labels indicating association to TLSA or SRV records, etc.) and whether there are NS records detected (i.e., it is a zone).

-s,  --recursive-servers server[,server...]

Query the specified recursive resolver(s), rather than using those specified in /etc/resolv.conf.

Each server specified may either be an address (IPv4 or IPv6), a domain name (which will be resolved to an address using the standard resolution process), or both, using the syntax name=address.  Note that when both a name and an address are specified (name=address), the name is only used for identification purposes, and it doesn't matter whether the name resolves to the corresponding address (or at all, for that matter).  IPv6 addresses must be wrapped in square brackets, e.g., "[2001:db8::1]".

Each server value may optionally be suffixed with a numeric port on which the server should be contacted.  If not specified, the standard DNS port, 53, is used.

The following are example server values:






This option cannot be used in conjunction with -A.

-A,  --authoritative-analysis

Query authoritative servers, rather than (the default) recursive servers.

-x,  --authoritative-servers domain[+]:server[,server...]

Treat the specified servers as authoritative for a domain, rather than learning authoritative servers by following delegations.  This option dictates which servers will be queried for a domain, but the servers specified will not be used to check NS or glue record consistency with the child; for that behavior, see -N.

The default behavior is to identify and query servers authoritative for ancestors of the specified domain, if other options so dictate.  However, if the domain ends in "+", then queries aren't issued for servers authoritative for ancestor domains of the domain.  For example, with the following command:

dnsviz probe -A -x example.com:ns1.example.com example.com

the com servers will be queried for DS records for example.com.  However, if the following is used:

dnsviz probe -A -x example.com+:ns1.example.com example.com

no queries are performed at com servers or above, including DS records for example.com.

See -s for the syntax used for designating servers.  However, unlike the -s option, a zone file may be specified in lieu of a server name and/or address, in which case an instance of named(8) is started, the zone is served from that instance, and queries for the domain are directed to the local instance of named(8) serving that zone.  For example, if example.com.zone is a file containing the contents of the example.com zone, the following command could be used to specify that the zone file should be used:

dnsviz probe -A -x example.com:example.com.zone example.com

This option may be used multiple times on the command line.

This option can only be used in conjunction with -A.

-N,  --delegation-information domain:server[,server...]

Use the specified delegation information for a domain, i.e., the NS and glue records for the domain, which would be served by the domain's parent.  This is used for testing new delegations or testing a potential change to a delegation.

This option has similar usage to that of the -x option.  The major difference is that the server names supplied comprise the NS record set, and the addresses supplied represent glue records.  Thus if there are discrepancies between the authoritative responses for the NS RRset and glue and what is supplied on the command line, an error will be reported when the output is subsequently assessed, e.g., using dnsviz-grok(1).

In lieu of specifying the record data itself on the command line, a file may be specified, which contains the delegation NS and glue records for the domain.

-D,  --ds domain:ds[,ds...]

Use the specified delegation signer (DS) records for a domain.  This is used in conjunction with the -N option for testing the introduction or change of DS records.

The DS records themselves are specified using the the textual representation of their record data.  For example the following DS records for example.com:

31589 8 1 3490A6806D47F17A34C29E2CE80E8A999FFBE4BE

31589 8 2 CDE0D742D6998AA554A92D890F8184C698CFAC8A26FA59875A990C03 E576343C

would be specified by passing this value to -D:

"31589 8 1 3490A6806D47F17A34C29E2CE80E8A999FFBE4BE,

  31589 8 2 CDE0D742D6998AA554A92D890F8184C698CFAC8A26FA59875A990C03 E576343C"

In lieu of specifying the record data itself on the command line, a file may be specified, which contains the DS records.  For example:

dnsviz probe -D example.com:dsset-example.com.

This option must be used in conjunction with the -N option.

-n,  --nsid

Use the NSID EDNS option with every DNS query issued.

-e,  --client-subnet subnet[:prefix_len]

Use the EDNS Client Subnet option with every DNS query issued, using the specified subnet and prefix_len as values.  If prefix is not specified, the prefix is the length of the entire address.

-c,  --cookie cookie

Send the specified DNS client cookie with every DNS query issued.  The value specified is for a client cookie only and thus should be exactly 64 bits long. The value for the cookie is specified using hexadecimal representation, e.g., deadbeef1580f00d.

If the -c option is not used, the default behavior is for a DNS client cookie to be generated randomly to be sent with queries.  If an empty string is specified, then DNS cookies are disabled.

-E,  --edns

Issue queries to check EDNS compatibility of servers.

If this option is used, each server probed will be queried with "future" EDNS settings, the respective responses can later be assessed for proper behavior. These settings include future EDNS versions (i.e., > 0), unknown options, and unknown flags.

-o,  --output-file filename

Write the output to the specified file instead of to standard output, which is the default.

-p,  --pretty-output

Output "pretty" instead of minimal JSON output, i.e., using indentation and newlines.  Note that this is the default when the output is a TTY.


Display the usage and exit.

Exit Codes

The exit codes are:


Program terminated normally.


Incorrect usage.


The network was unavailable for diagnostic queries.


There was an error processing the input or saving the output.


Program execution was interrupted, or an unknown error occurred.

See Also

dnsviz(1), dnsviz-grok(1), dnsviz-graph(1), dnsviz-print(1), dnsviz-query(1)

Referenced By

dnsviz(1), dnsviz-graph(1), dnsviz-grok(1), dnsviz-print(1), dnsviz-query(1).

27 Sep 2021 0.9.4