dig

dig (domain information groper) befragt DNS-Server

Beschreibung

dig ist ein flexibles Werkzeug zur Abfrage von DNS-Nameservern

• Es führt DNS-Abfragen durch und zeigt die Antworten an, die von dem/den abgefragten Nameserver(n) zurückgegeben werden.
• Die meisten DNS-Administratoren verwenden dig für die Fehlersuche bei DNS-Problemen, da es flexibel, einfach zu bedienen und übersichtlich in der Ausgabe ist.
• Andere Lookup-Tools haben in der Regel weniger Funktionalität als dig.

Obwohl dig normalerweise mit Befehlszeilenargumenten verwendet wird, verfügt es auch über einen Batch-Modus, um Lookup-Anfragen aus einer Datei zu lesen.

• Eine kurze Zusammenfassung der Befehlszeilenargumente und Optionen wird ausgegeben, wenn die Option -h angegeben wird.
• Die BIND 9-Implementierung von dig erlaubt es, mehrere Suchanfragen von der Kommandozeile aus zu stellen.

Wenn es nicht angewiesen wird, einen bestimmten Nameserver abzufragen, versucht dig jeden der in /etc/resolv.conf aufgeführten Server.

• Wenn keine brauchbaren Serveradressen gefunden werden, sendet dig die Anfrage an den lokalen Host.

Wenn keine Befehlszeilenargumente oder Optionen angegeben werden, führt dig eine NS-Abfrage für "." (die Wurzel) durch.

Es ist möglich, über ${HOME}/.digrc benutzerspezifische Voreinstellungen für dig zu setzen

• Diese Datei wird gelesen und alle darin enthaltenen Optionen werden vor den Befehlszeilenargumenten angewendet.
• Die Option -r deaktiviert diese Funktion für Skripte, die ein vorhersehbares Verhalten benötigen.

Die Klassennamen IN und CH überschneiden sich mit den Top-Level-Domainnamen IN und CH

• Verwenden Sie entweder die Optionen -t und -c, um den Typ und die Klasse anzugeben, verwenden Sie die Option -q, um den Domänennamen anzugeben, oder verwenden Sie "IN." und "CH.", wenn Sie diese Top-Level-Domänen nachschlagen.

Installation

# apt install dnsutils

Syntax

$ dig [@Server] [Domain] [Typ] [-x IP-Adresse]

Parameter

Resource Record Typ

Typ	Beschreibung
ANY	alle Einträge
A	IPv4 Record eines Hosts
AAAA	IPv6 Record eines Hosts
CNAME	Kanonischer Name, Zuordnung von Aliassen
MX	Mail Exchanger
NS	Hostname eines autoritativen Nameservers
PTR	Domain Name Pointer (um IP-Adressen Namen zuzuweisen)
SOA	Start of Authority
SRV	Angebotene Dienste
TXT	Beliebiger Text

Weitere Parameter

Typ	Beschreibung
+short	gibt eine sehr kurze Antwort, zB die reine IP der Domain
-f query.txt	file - Eingabe-Datei für mehrere Abfragen
-4 / -6	IPv4 / IPv6
-x	Rückwärtssuche... IP der Domain suchen

Anwendung

A typical invocation of dig looks like:

dig @server name type

where:

server is the name or IP address of the name server to query.

• This can be an IPv4 address in dotted-decimal notation or an IPv6 address in colon-delimited notation.
• When the supplied server argument is a hostname, dig resolves that name before querying that name server.

If no server argument is provided, dig consults /etc/resolv.conf; if an address is found there, it queries the name server at that address.

• If either of the -4 or -6 options are in use, then only addresses for the corresponding transport are tried.
• If no usable addresses are found, dig sends the query to the local host.
• The reply from the name server that responds is displayed.

name is the name of the resource record that is to be looked up.

type indicates what type of query is required - ANY, A, MX, SIG, etc. type can be any valid query type.

• If no type argument is supplied, dig performs a lookup for an A record.

Alle Adressen für einen Domain-Namen

$ dig +nocmd google.com a +noall +answer

Alias-Domänennamen

$ dig +nocmd mail.google.com cname +noall +answer

TXT-Einträge

$ dig +nocmd google.com txt +noall +answer

Mailserver

$ dig +nocmd google.com mx +noall +answer

Autorisierenden Nameserver Domäne

$ dig +nocmd google.com ns +noall +answer

Aller DNS-Einträge

$ dig +nocmd google.com any +noall +answer

Dokumentation

Man-Pages

$ man dig

Links

Weblinks

1. https://geek-university.com/linux-deutsch/dig-befehl/
2. https://linuxize.com/post/how-to-use-dig-command-to-query-dns-in-linux/ (Englisch)
3. https://wiki.ubuntuusers.de/dig/

Kontrollfragen

Testfrage 1

Antwort1

Testfrage 2

Antwort2

Testfrage 3

Antwort3

Testfrage 4

Antwort4

Testfrage 5

Antwort5

Manpage

DIG(1) BIND 9 DIG(1)

NAME

dig - DNS lookup utility

SYNOPSIS

dig [@server] [-b address] [-c class] [-f filename] [-k filename] [-m] [-p port#] [-q name] [-t type] [-v] [-x addr] [-y [hmac:]name:key] [ [-4] | [-6] ] [name] [type] [class] [queryopt...]

dig [-h]

dig [global-queryopt...] [query...]

SIMPLE USAGE

A typical invocation of dig looks like

dig @server name type

server

Name or IP address of the name server to query.

• This can be an IPv4 address in dotted-decimal notation or an IPv6 address in colon-delimited notation.
• When the supplied server argument is a hostname, dig resolves that name before querying that name server.

If no server argument is provided, dig consults /etc/resolv.conf; if an address is found there, it queries the name server at that address.

• If either of the -4 or -6 options are in use, then only addresses for the corresponding transport are tried.
• If no usable addresses are found, dig sends the query to the local host.
• The reply from the name server that responds is displayed.

name

Name of the resource record that is to be looked up.

type

Indicates what type of query is required - ANY, A, MX, SIG, etc. type can be any valid query type.

• If no type argument is supplied, dig performs a lookup for an A record.

DIG(1) BIND 9 DIG(1)

NAME

dig - DNS lookup utility

SYNOPSIS

dig [@server] [-b address] [-c class] [-f filename] [-k filename] [-m] [-p port#] [-q name] [-t type] [-v] [-x addr] [-y [hmac:]name:key] [ [-4] | [-6] ] [name] [type] [class] [queryopt...]

dig [-h]

dig [global-queryopt...] [query...]

DESCRIPTION

dig is a flexible tool for interrogating DNS name servers.

• It performs DNS lookups and displays the answers that are returned from the name server(s) that were queried.
• Most DNS administrators use dig to troubleshoot DNS problems because of its flexibility, ease of use, and clarity of output.
• Other lookup tools tend to have less functionality than dig.

Although dig is normally used with command-line arguments, it also has a batch mode of operation for reading lookup requests from a file.

• A brief summary of its command-line arguments and options is printed when the -h option is given.
• The BIND 9 implementation of dig allows multiple lookups to be issued from the command line.

Unless it is told to query a specific name server, dig tries each of the servers listed in /etc/resolv.conf.

• If no usable server addresses are found, dig sends the query to the local host.

When no command-line arguments or options are given, dig performs an NS query for "." (the root).

It is possible to set per-user defaults for dig via ${HOME}/.digrc.

• This file is read and any options in it are applied before the command-line arguments.
• The -r option disables this feature, for scripts that need predictable behavior.

The IN and CH class names overlap with the IN and CH top-level domain names.

• Either use the -t and -c options to specify the type and class, use the -q to specify the domain name, or use "IN." and "CH." when looking up these top-level domains.

OPTIONEN

-4 Diese Option gibt an, dass nur IPv4 verwendet werden soll.

-6 Diese Option zeigt an, dass nur IPv6 verwendet werden soll.

-b Adresse[#Port] Mit dieser Option wird die Quell-IP-Adresse der Abfrage festgelegt.

• Die Adresse muss eine gültige Adresse auf einer der Netzwerkschnittstellen des Hosts sein, oder "0.0.0.0" oder "::".
• Ein optionaler Port kann durch Anhängen von #port angegeben werden.

-c Klasse Mit dieser Option wird die Abfrageklasse festgelegt.

• Die Standardklasse ist IN; andere Klassen sind HS für

Hesiod-Datensätze oder CH für Chaosnet-Datensätze.

-f Datei Mit dieser Option wird der Batch-Modus eingestellt, in dem dig eine Liste von Suchanfragen aus der angegebenen Datei liest.

• Jede Zeile in der Datei sollte so aufgebaut sein, wie sie als Abfrage an dig über die Kommandozeilenschnittstelle dargestellt werden würde.

-h Gibt eine Zusammenfassung der Nutzung aus.

-k Schlüsseldatei Diese Option weist dig an, Abfragen mit TSIG oder SIG(0) unter Verwendung eines aus der angegebenen Datei gelesenen Schlüssels zu signieren.

• Schlüsseldateien können mit tsig-keygen erzeugt werden.
• Bei der Verwendung von TSIG-Authentifizierung mit dig muss der angefragte Nameserver den verwendeten Schlüssel und Algorithmus kennen.
• In BIND wird dies durch entsprechende Schlüssel- und Server-Anweisungen in named.conf für TSIG und durch Nachschlagen des KEY-Eintrags in den Zonendaten für SIG(0) erreicht.

-m Diese Option aktiviert das Debugging der Speichernutzung.

-p Anschluss Mit dieser Option wird die Abfrage an einen nicht standardmäßigen Port auf dem Server gesendet, anstelle des Standardports 53.

• Diese Option wird verwendet, um einen Nameserver zu testen, der so konfiguriert wurde, dass er auf Abfragen an einer nicht standardmäßigen Portnummer wartet.

-q Name Diese Option gibt den abzufragenden Domänennamen an.

• Dies ist nützlich, um den Namen von anderen Argumenten zu unterscheiden.

-r Diese Option gibt an, dass Optionen aus ${HOME}/.digrc nicht gelesen werden sollen.

• Dies ist nützlich für Skripte, die ein vorhersehbares Verhalten benötigen.

-t Typ Diese Option gibt den abzufragenden Ressourcendatensatztyp an, der jeder gültige Abfragetyp sein kann.

• Wenn es sich um einen Ressourcendatensatztyp handelt, der von BIND 9 unterstützt wird, kann er durch die Typ-Mnemonik angegeben werden (wie NS oder AAAA).
• Der Standardabfragetyp ist A, es sei denn, die Option -x wird angegeben, um eine Rückwärtssuche zu ermöglichen.
• Ein Zonentransfer kann durch die Angabe eines Typs AXFR angefordert werden.
• Wenn ein inkrementeller Zonentransfer (IXFR) erforderlich ist, setzen Sie den Typ auf ixfr=N.
• Der inkrementelle Zonentransfer enthält alle Änderungen, die an der Zone vorgenommen wurden, seit die Seriennummer im SOA-Eintrag der Zone N war.

Alle Ressourcendatensatztypen können als TYPEnn ausgedrückt werden, wobei nn die Nummer des Typs ist.

• Wenn der Ressourcendatentyp in BIND 9 nicht unterstützt wird, wird das Ergebnis wie in RFC 3597 beschrieben angezeigt.

-u Diese Option gibt an, dass die Druckabfragezeiten in Mikrosekunden statt in Millisekunden angegeben werden sollen.

-v Diese Option gibt die Versionsnummer aus und beendet das Programm.

-x addr Mit dieser Option werden vereinfachte Reverse-Lookups für die Zuordnung von Adressen zu Namen eingestellt.

• addr ist eine IPv4-Adresse in punktierter Dezimalschreibweise oder eine durch Doppelpunkte getrennte IPv6-Adresse.
• Wenn die Option

Bei Verwendung der Option -x müssen die Argumente name, class und type nicht angegeben werden. dig führt automatisch eine Suche nach einem Namen wie 94.2.0.192.in-addr.arpa durch und setzt den Abfragetyp und die Klasse auf PTR bzw. IN.

• IPv6-Adressen werden im Nibble-Format unter der IP6.ARPA-Domäne nachgeschlagen.

-y [hmac:]keyname:secret Diese Option signiert Abfragen unter Verwendung von TSIG mit dem angegebenen Authentifizierungsschlüssel. keyname ist der Name des Schlüssels, und secret ist das base64-kodierte gemeinsame Geheimnis.

• hmac ist der Name des Schlüsselalgorithmus; gültige Auswahlmöglichkeiten sind hmac-md5, hmac-sha1, hmac-sha224, hmac-sha256, hmac-sha384 oder hmac-sha512.
• Wenn hmac nicht angegeben wird, ist der Standard hmac-md5; wenn MD5

deaktiviert wurde, ist die Vorgabe hmac-sha256.

HINWEIS: Es sollte nur die Option -k und nicht die Option -y verwendet werden, da bei -y das gemeinsame Geheimnis als Kommandozeilenargument im Klartext übergeben wird.

• Dies kann in der Ausgabe von ps1 oder in einer von der Shell des Benutzers geführten Verlaufsdatei sichtbar sein.

QUERY OPTIONS

dig provides a number of query options which affect the way in which lookups are made and the results displayed.

• Some of these set or reset flag bits in the query header, some determine which sections of the answer get printed, and others determine the timeout and retry strategies.

Each query option is identified by a keyword preceded by a plus sign (+).

• Some keywords set or reset an option; these may be preceded by the string no to negate the meaning of that keyword.

Other keywords assign values to options, like the timeout interval.

• They have the form

+keyword=value.

• Keywords may be abbreviated, provided the abbreviation is unambiguous; for example, +cd is equivalent to +cdflag.
• The query options are:

+aaflag, +noaaflag This option is a synonym for +aaonly, +noaaonly.

+aaonly, +noaaonly This option sets the aa flag in the query.

+additional, +noadditional This option displays [or does not display] the additional section of a reply.

• The default is to display it.

+adflag, +noadflag This option sets [or does not set] the AD (authentic data) bit in the query.

• This requests the server to return whether all of the answer and authority sections have been validated as secure, according to the security policy of the server.
• AD=1 indicates that all records have been validated as secure and the answer is not from a OPT-OUT range.

AD=0 indicates that some part of the answer was insecure or not validated. This bit is set by default.

+all, +noall This option sets or clears all display flags.

+answer, +noanswer This option displays [or does not display] the answer section of a reply.

• The default is to display it.

+authority, +noauthority This option displays [or does not display] the authority section of a reply.

• The default is to display it.

+badcookie, +nobadcookie This option retries the lookup with a new server cookie if a BADCOOKIE response is received.

+besteffort, +nobesteffort This option attempts to display the contents of messages which are malformed.

• The default is to not display malformed answers.

+bufsize[=B] This option sets the UDP message buffer size advertised using EDNS0 to B bytes. The maximum and minimum sizes of this buffer are 65535 and 0, respectively. +bufsize restores the default buffer size.

+cd, +cdflag, +nocdflag This option sets [or does not set] the CD (checking disabled) bit in the query.

• This requests the server to not perform DNSSEC validation of responses.

+class, +noclass This option displays [or does not display] the CLASS when printing the record.

+cmd, +nocmd This option toggles the printing of the initial comment in the output, identifying the version of dig and the query options that have been applied.

• This option always has a global effect; it cannot be set globally and then overridden on a per-lookup basis.
• The default is to print this comment.

+comments, +nocomments This option toggles the display of some comment lines in the output, with information about the packet header and OPT pseudosection, and the names of the response section. The default is to print these comments.

Other types of comments in the output are not affected by this option, but can be controlled using other command-line switches.

• These include +cmd, +question, +stats, and

+rrcomments.

+cookie=####, +nocookie This option sends [or does not send] a COOKIE EDNS option, with an optional value. Replaying a COOKIE from a previous response allows the server to identify a previous client.

• The default is +cookie.

+cookie is also set when +trace is set to better emulate the default queries from a nameserver.

+crypto, +nocrypto This option toggles the display of cryptographic fields in DNSSEC records.

• The contents of these fields are unnecessary for debugging most DNSSEC validation failures and removing them makes it easier to see the common failures.
• The default is to display the fields.
• When omitted, they are replaced by the string [omitted] or, in the DNSKEY case, the key ID is displayed as the replacement, e.g. [ key id = value ].

+defname, +nodefname This option, which is deprecated, is treated as a synonym for +search, +nosearch.

+dns64prefix, +nodns64prefix Lookup IPV4ONLY.ARPA AAAA and print any DNS64 prefixes found.

+dnssec, +do, +nodnssec, +nodo This option requests that DNSSEC records be sent by setting the DNSSEC OK (DO) bit in the OPT record in the additional section of the query.

+domain=somename This option sets the search list to contain the single domain somename, as if specified in a domain directive in /etc/resolv.conf, and enables search list processing as if the +search option were given.

+dscp=value This option formerly set the DSCP value used when sending a query. It is now obsolete, and has no effect.

+edns[=#], +noedns This option specifies the EDNS version to query with.

• Valid values are 0 to 255.

Setting the EDNS version causes an EDNS query to be sent. +noedns clears the remembered EDNS version.

• EDNS is set to 0 by default.

+ednsflags[=#], +noednsflags This option sets the must-be-zero EDNS flags bits (Z bits) to the specified value. Decimal, hex, and octal encodings are accepted.

• Setting a named flag (e.g., DO) is silently ignored.
• By default, no Z bits are set.

+ednsnegotiation, +noednsnegotiation This option enables/disables EDNS version negotiation.

• By default, EDNS version negotiation is enabled.

+ednsopt[=code[:value]], +noednsopt This option specifies the EDNS option with code point code and an optional payload of value as a hexadecimal string.

• code can be either an EDNS option name (for example, NSID

or ECS) or an arbitrary numeric value. +noednsopt clears the EDNS options to be sent.

+expire, +noexpire This option sends an EDNS Expire option.

+fail, +nofail This option indicates that named should try [or not try] the next server if a SERVFAIL is received.

• The default is to not try the next server, which is the reverse of normal stub resolver behavior.

+fuzztime[=value], +nofuzztime This option allows the signing time to be specified when generating signed messages. If a value is specified it is the seconds since 00:00:00 January 1, 1970 UTC ignoring leap seconds. If no value is specified 1646972129 (Fri 11 Mar 2022 04:15:29 UTC) is used. The default is +nofuzztime and the current time is used.

+header-only, +noheader-only This option sends a query with a DNS header without a question section.

• The default is to add a question section.
• The query type and query name are ignored when this is set.

+https[=value], +nohttps This option indicates whether to use DNS over HTTPS (DoH) when querying name servers. When this option is in use, the port number defaults to 443. The HTTP POST request mode is used when sending the query.

If value is specified, it will be used as the HTTP endpoint in the query URI; the default is /dns-query.

• So, for example, dig @example.com +https will use the URI

https://example.com/dns-query.

+https-get[=value], +nohttps-get Similar to +https, except that the HTTP GET request mode is used when sending the query.

+https-post[=value], +nohttps-post Same as +https.

+http-plain[=value], +nohttp-plain Similar to +https, except that HTTP queries will be sent over a non-encrypted channel. When this option is in use, the port number defaults to 80 and the HTTP request mode is POST.

+http-plain-get[=value], +nohttp-plain-get Similar to +http-plain, except that the HTTP request mode is GET.

+http-plain-post[=value], +nohttp-plain-post Same as +http-plain.

+identify, +noidentify This option shows [or does not show] the IP address and port number that supplied the answer, when the +short option is enabled.

• If short form answers are requested, the default is not to show the source address and port number of the server that provided the answer.

+idnin, +noidnin This option processes [or does not process] IDN domain names on input.

• This requires IDN

SUPPORT to have been enabled at compile time.

The default is to process IDN input when standard output is a tty. The IDN processing on input is disabled when dig output is redirected to files, pipes, and other non-tty file descriptors.

+idnout, +noidnout This option converts [or does not convert] puny code on output.

• This requires IDN

SUPPORT to have been enabled at compile time.

The default is to process puny code on output when standard output is a tty.

• The puny code processing on output is disabled when dig output is redirected to files, pipes, and other non-tty file descriptors.

+ignore, +noignore This option ignores [or does not ignore] truncation in UDP responses instead of retrying with TCP.

• By default, TCP retries are performed.

+keepalive, +nokeepalive This option sends [or does not send] an EDNS Keepalive option.

+keepopen, +nokeepopen This option keeps [or does not keep] the TCP socket open between queries, and reuses it rather than creating a new TCP socket for each lookup.

• The default is +nokeepopen.

+multiline, +nomultiline This option prints [or does not print] records, like the SOA records, in a verbose multi-line format with human-readable comments.

• The default is to print each record on a single line to facilitate machine parsing of the dig output.

+ndots=D This option sets the number of dots (D) that must appear in name for it to be considered absolute.

• The default value is that defined using the ndots statement in

/etc/resolv.conf, or 1 if no ndots statement is present.

• Names with fewer dots are interpreted as relative names, and are searched for in the domains listed in the search or domain directive in /etc/resolv.conf if +search is set.

+nsid, +nonsid When enabled, this option includes an EDNS name server ID request when sending a query.

+nssearch, +nonssearch When this option is set, dig attempts to find the authoritative name servers for the zone containing the name being looked up, and display the SOA record that each name server has for the zone. Addresses of servers that did not respond are also printed.

+onesoa, +noonesoa When enabled, this option prints only one (starting) SOA record when performing an AXFR. The default is to print both the starting and ending SOA records.

+opcode=value, +noopcode When enabled, this option sets (restores) the DNS message opcode to the specified value. The default value is QUERY (0).

+padding=value This option pads the size of the query packet using the EDNS Padding option to blocks of value bytes.

• For example, +padding=32 causes a 48-byte query to be padded to 64 bytes.

The default block size is 0, which disables padding; the maximum is 512.

• Values are ordinarily expected to be powers of two, such as 128; however, this is not mandatory.

Responses to padded queries may also be padded, but only if the query uses TCP or DNS COOKIE.

+qid=value This option specifies the query ID to use when sending queries.

+qr, +noqr This option toggles the display of the query message as it is sent.

• By default, the query is not printed.

+question, +noquestion This option toggles the display of the question section of a query when an answer is returned.

• The default is to print the question section as a comment.

+raflag, +noraflag This option sets [or does not set] the RA (Recursion Available) bit in the query.

• The default is +noraflag.
• This bit is ignored by the server for QUERY.

+rdflag, +nordflag This option is a synonym for +recurse, +norecurse.

+recurse, +norecurse This option toggles the setting of the RD (recursion desired) bit in the query. This bit is set by default, which means dig normally sends recursive queries.

• Recursion is automatically disabled when the +nssearch or +trace query option is used.

+retry=T This option sets the number of times to retry UDP and TCP queries to server to T instead of the default, 2. Unlike +tries, this does not include the initial query.

+rrcomments, +norrcomments This option toggles the display of per-record comments in the output (for example, human-readable key information about DNSKEY records).

• The default is not to print record comments unless multiline mode is active.

+search, +nosearch This option uses [or does not use] the search list defined by the searchlist or domain directive in resolv.conf, if any.

• The search list is not used by default.

ndots from resolv.conf (default 1), which may be overridden by +ndots, determines whether the name is treated as relative and hence whether a search is eventually performed.

+short, +noshort This option toggles whether a terse answer is provided.

• The default is to print the answer in a verbose form.
• This option always has a global effect; it cannot be set globally and then overridden on a per-lookup basis.

+showbadcookie, +noshowbadcookie This option toggles whether to show the message containing the BADCOOKIE rcode before retrying the request or not.

• The default is to not show the messages.

+showsearch, +noshowsearch This option performs [or does not perform] a search showing intermediate results.

+sigchase, +nosigchase This feature is now obsolete and has been removed; use delv instead.

+split=W This option splits long hex- or base64-formatted fields in resource records into chunks of W characters (where W is rounded up to the nearest multiple of 4). +nosplit or +split=0 causes fields not to be split at all.

• The default is 56 characters, or 44

characters when multiline mode is active.

+stats, +nostats This option toggles the printing of statistics.

• when the query was made, the size of the reply, etc.
• The default behavior is to print the query statistics as a comment after each lookup.

+subnet=addr[/prefix-length], +nosubnet This option sends [or does not send] an EDNS CLIENT-SUBNET option with the specified IP address or network prefix.

dig +subnet=0.0.0.0/0, or simply dig +subnet=0 for short, sends an EDNS CLIENT-SUBNET option with an empty address and a source prefix-length of zero, which signals a resolver that the client's address information must not be used when resolving this query.

+tcflag, +notcflag This option sets [or does not set] the TC (TrunCation) bit in the query.

• The default is

+notcflag.

• This bit is ignored by the server for QUERY.

+tcp, +notcp This option indicates whether to use TCP when querying name servers. The default behavior is to use UDP unless a type any or ixfr=N query is requested, in which case the default is TCP.

• AXFR queries always use TCP.
• To prevent retry over TCP when TC=1 is returned from a UDP query, use +ignore.

+timeout=T This option sets the timeout for a query to T seconds.

• The default timeout is 5 seconds.

An attempt to set T to less than 1 is silently set to 1.

+tls, +notls This option indicates whether to use DNS over TLS (DoT) when querying name servers.

• When this option is in use, the port number defaults to 853.

+tls-ca[=file-name], +notls-ca This option enables remote server TLS certificate validation for DNS transports, relying on TLS.

• Certificate authorities certificates are loaded from the specified PEM file

(file-name).

• If the file is not specified, the default certificates from the global certificates store are used.

+tls-certfile=file-name, +tls-keyfile=file-name, +notls-certfile, +notls-keyfile These options set the state of certificate-based client authentication for DNS transports, relying on TLS.

• Both certificate chain file and private key file are expected to be in PEM format. Both options must be specified at the same time.

+tls-hostname=hostname, +notls-hostname This option makes dig use the provided hostname during remote server TLS certificate verification.

• Otherwise, the DNS server name is used.
• This option has no effect if

+tls-ca is not specified.

+topdown, +notopdown This feature is related to dig +sigchase, which is obsolete and has been removed.

• Use delv instead.

+trace, +notrace This option toggles tracing of the delegation path from the root name servers for the name being looked up.

• Tracing is disabled by default.
• When tracing is enabled, dig makes iterative queries to resolve the name being looked up.
• It follows referrals from the root servers, showing the answer from each server that was used to resolve the lookup.

If @server is also specified, it affects only the initial query for the root zone name servers.

+dnssec is also set when +trace is set, to better emulate the default queries from a name server.

+tries=T This option sets the number of times to try UDP and TCP queries to server to T instead of the default, 3.

• If T is less than or equal to zero, the number of tries is silently rounded up to 1.

+trusted-key=#### This option formerly specified trusted keys for use with dig +sigchase.

• This feature is now obsolete and has been removed; use delv instead.

+ttlid, +nottlid This option displays [or does not display] the TTL when printing the record.

+ttlunits, +nottlunits This option displays [or does not display] the TTL in friendly human-readable time units of s, m, h, d, and w, representing seconds, minutes, hours, days, and weeks.

• This implies +ttlid.

+unknownformat, +nounknownformat This option prints all RDATA in unknown RR type presentation format (RFC 3597). The default is to print RDATA for known types in the type's presentation format.

+vc, +novc This option uses [or does not use] TCP when querying name servers.

• This alternate syntax to +tcp is provided for backwards compatibility.
• The vc stands for "virtual circuit."

+yaml, +noyaml When enabled, this option prints the responses (and, if +qr is in use, also the outgoing queries) in a detailed YAML format.

+zflag, +nozflag This option sets [or does not set] the last unassigned DNS header flag in a DNS query. This flag is off by default.

MULTIPLE QUERIES

The BIND 9 implementation of dig supports specifying multiple queries on the command line (in addition to supporting the -f batch file option).

• Each of those queries can be supplied with its own set of flags, options, and query options.

In this case, each query argument represents an individual query in the command-line syntax described above.

• Each consists of any of the standard options and flags, the name to be looked up, an optional query type and class, and any query options that should be applied to that query.

A global set of query options, which should be applied to all queries, can also be supplied. These global query options must precede the first tuple of name, class, type, options, flags, and query options supplied on the command line.

• Any global query options (except +cmd and

+short options) can be overridden by a query-specific set of query options.

• For example:

dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr

shows how dig can be used from the command line to make three lookups.

• an ANY query for www.isc.org, a reverse lookup of 127.0.0.1, and a query for the NS records of isc.org.
• A global query option of +qr is applied, so that dig shows the initial query it made for each lookup.

The final query has a local query option of +noqr which means that dig does not print the initial query when it looks up the NS records for isc.org.

IDN SUPPORT

If dig has been built with IDN (internationalized domain name) support, it can accept and display non-ASCII domain names.

• dig appropriately converts character encoding of a domain name before sending a request to a DNS server or displaying a reply from the server. To turn off

IDN support, use the parameters +idnin and +idnout, or define the IDN_DISABLE environment variable.

RETURN CODES

 0     DNS response received, including NXDOMAIN status
 1     Usage error
 8     Couldn't open batch file
 9     No reply from server
10     Internal error

FILES

/etc/resolv.conf
${HOME}/.digrc

SEE ALSO

delv(1), host(1), named(8), dnssec-keygen(8), RFC 1035.

QUERY OPTIONS

dig provides a number of query options which affect the way in which lookups are made and the results displayed.

• Some of these set or reset flag bits in the query header, some determine which sections of the answer get printed, and others determine the timeout and retry strategies.

Each query option is identified by a keyword preceded by a plus sign (+).

• Some keywords set or reset an option; these may be preceded by the string no to negate the meaning of that keyword.

Other keywords assign values to options, like the timeout interval.

• They have the form

+keyword=value.

• Keywords may be abbreviated, provided the abbreviation is unambiguous; for example, +cd is equivalent to +cdflag.
• The query options are:

+aaflag, +noaaflag This option is a synonym for +aaonly, +noaaonly.

+aaonly, +noaaonly This option sets the aa flag in the query.

+additional, +noadditional This option displays [or does not display] the additional section of a reply.

• The default is to display it.

+adflag, +noadflag This option sets [or does not set] the AD (authentic data) bit in the query.

• This requests the server to return whether all of the answer and authority sections have been validated as secure, according to the security policy of the server.
• AD=1 indicates that all records have been validated as secure and the answer is not from a OPT-OUT range.

AD=0 indicates that some part of the answer was insecure or not validated. This bit is set by default.

+all, +noall This option sets or clears all display flags.

+answer, +noanswer This option displays [or does not display] the answer section of a reply.

• The default is to display it.

+authority, +noauthority This option displays [or does not display] the authority section of a reply.

• The default is to display it.

+badcookie, +nobadcookie This option retries the lookup with a new server cookie if a BADCOOKIE response is received.

+besteffort, +nobesteffort This option attempts to display the contents of messages which are malformed.

• The default is to not display malformed answers.

+bufsize[=B] This option sets the UDP message buffer size advertised using EDNS0 to B bytes. The maximum and minimum sizes of this buffer are 65535 and 0, respectively. +bufsize restores the default buffer size.

+cd, +cdflag, +nocdflag This option sets [or does not set] the CD (checking disabled) bit in the query.

• This requests the server to not perform DNSSEC validation of responses.

+class, +noclass This option displays [or does not display] the CLASS when printing the record.

+cmd, +nocmd This option toggles the printing of the initial comment in the output, identifying the version of dig and the query options that have been applied.

• This option always has a global effect; it cannot be set globally and then overridden on a per-lookup basis.
• The default is to print this comment.

+comments, +nocomments This option toggles the display of some comment lines in the output, with information about the packet header and OPT pseudosection, and the names of the response section. The default is to print these comments.

Other types of comments in the output are not affected by this option, but can be controlled using other command-line switches.

• These include +cmd, +question, +stats, and

+rrcomments.

+cookie=####, +nocookie This option sends [or does not send] a COOKIE EDNS option, with an optional value. Replaying a COOKIE from a previous response allows the server to identify a previous client.

• The default is +cookie.

+cookie is also set when +trace is set to better emulate the default queries from a nameserver.

+crypto, +nocrypto This option toggles the display of cryptographic fields in DNSSEC records.

• The contents of these fields are unnecessary for debugging most DNSSEC validation failures and removing them makes it easier to see the common failures.
• The default is to display the fields.
• When omitted, they are replaced by the string [omitted] or, in the DNSKEY case, the key ID is displayed as the replacement, e.g. [ key id = value ].

+defname, +nodefname This option, which is deprecated, is treated as a synonym for +search, +nosearch.

+dns64prefix, +nodns64prefix Lookup IPV4ONLY.ARPA AAAA and print any DNS64 prefixes found.

+dnssec, +do, +nodnssec, +nodo This option requests that DNSSEC records be sent by setting the DNSSEC OK (DO) bit in the OPT record in the additional section of the query.

+domain=somename This option sets the search list to contain the single domain somename, as if specified in a domain directive in /etc/resolv.conf, and enables search list processing as if the +search option were given.

+dscp=value This option formerly set the DSCP value used when sending a query. It is now obsolete, and has no effect.

+edns[=#], +noedns This option specifies the EDNS version to query with.

• Valid values are 0 to 255.

Setting the EDNS version causes an EDNS query to be sent. +noedns clears the remembered EDNS version.

• EDNS is set to 0 by default.

+ednsflags[=#], +noednsflags This option sets the must-be-zero EDNS flags bits (Z bits) to the specified value. Decimal, hex, and octal encodings are accepted.

• Setting a named flag (e.g., DO) is silently ignored.
• By default, no Z bits are set.

+ednsnegotiation, +noednsnegotiation This option enables/disables EDNS version negotiation.

• By default, EDNS version negotiation is enabled.

+ednsopt[=code[:value]], +noednsopt This option specifies the EDNS option with code point code and an optional payload of value as a hexadecimal string.

• code can be either an EDNS option name (for example, NSID

or ECS) or an arbitrary numeric value. +noednsopt clears the EDNS options to be sent.

+expire, +noexpire This option sends an EDNS Expire option.

+fail, +nofail This option indicates that named should try [or not try] the next server if a SERVFAIL is received.

• The default is to not try the next server, which is the reverse of normal stub resolver behavior.

+fuzztime[=value], +nofuzztime This option allows the signing time to be specified when generating signed messages. If a value is specified it is the seconds since 00:00:00 January 1, 1970 UTC ignoring leap seconds. If no value is specified 1646972129 (Fri 11 Mar 2022 04:15:29 UTC) is used. The default is +nofuzztime and the current time is used.

+header-only, +noheader-only This option sends a query with a DNS header without a question section.

• The default is to add a question section.
• The query type and query name are ignored when this is set.

+https[=value], +nohttps This option indicates whether to use DNS over HTTPS (DoH) when querying name servers. When this option is in use, the port number defaults to 443. The HTTP POST request mode is used when sending the query.

If value is specified, it will be used as the HTTP endpoint in the query URI; the default is /dns-query.

• So, for example, dig @example.com +https will use the URI

https://example.com/dns-query.

+https-get[=value], +nohttps-get Similar to +https, except that the HTTP GET request mode is used when sending the query.

+https-post[=value], +nohttps-post Same as +https.

+http-plain[=value], +nohttp-plain Similar to +https, except that HTTP queries will be sent over a non-encrypted channel. When this option is in use, the port number defaults to 80 and the HTTP request mode is POST.

+http-plain-get[=value], +nohttp-plain-get Similar to +http-plain, except that the HTTP request mode is GET.

+http-plain-post[=value], +nohttp-plain-post Same as +http-plain.

+identify, +noidentify This option shows [or does not show] the IP address and port number that supplied the answer, when the +short option is enabled.

• If short form answers are requested, the default is not to show the source address and port number of the server that provided the answer.

+idnin, +noidnin This option processes [or does not process] IDN domain names on input.

• This requires IDN

SUPPORT to have been enabled at compile time.

The default is to process IDN input when standard output is a tty. The IDN processing on input is disabled when dig output is redirected to files, pipes, and other non-tty file descriptors.

+idnout, +noidnout This option converts [or does not convert] puny code on output.

• This requires IDN

SUPPORT to have been enabled at compile time.

The default is to process puny code on output when standard output is a tty.

• The puny code processing on output is disabled when dig output is redirected to files, pipes, and other non-tty file descriptors.

+ignore, +noignore This option ignores [or does not ignore] truncation in UDP responses instead of retrying with TCP.

• By default, TCP retries are performed.

+keepalive, +nokeepalive This option sends [or does not send] an EDNS Keepalive option.

+keepopen, +nokeepopen This option keeps [or does not keep] the TCP socket open between queries, and reuses it rather than creating a new TCP socket for each lookup.

• The default is +nokeepopen.

+multiline, +nomultiline This option prints [or does not print] records, like the SOA records, in a verbose multi-line format with human-readable comments.

• The default is to print each record on a single line to facilitate machine parsing of the dig output.

+ndots=D This option sets the number of dots (D) that must appear in name for it to be considered absolute.

• The default value is that defined using the ndots statement in

/etc/resolv.conf, or 1 if no ndots statement is present.

• Names with fewer dots are interpreted as relative names, and are searched for in the domains listed in the search or domain directive in /etc/resolv.conf if +search is set.

+nsid, +nonsid When enabled, this option includes an EDNS name server ID request when sending a query.

+nssearch, +nonssearch When this option is set, dig attempts to find the authoritative name servers for the zone containing the name being looked up, and display the SOA record that each name server has for the zone. Addresses of servers that did not respond are also printed.

+onesoa, +noonesoa When enabled, this option prints only one (starting) SOA record when performing an AXFR. The default is to print both the starting and ending SOA records.

+opcode=value, +noopcode When enabled, this option sets (restores) the DNS message opcode to the specified value. The default value is QUERY (0).

+padding=value This option pads the size of the query packet using the EDNS Padding option to blocks of value bytes.

• For example, +padding=32 causes a 48-byte query to be padded to 64 bytes.

The default block size is 0, which disables padding; the maximum is 512.

• Values are ordinarily expected to be powers of two, such as 128; however, this is not mandatory.

Responses to padded queries may also be padded, but only if the query uses TCP or DNS COOKIE.

+qid=value This option specifies the query ID to use when sending queries.

+qr, +noqr This option toggles the display of the query message as it is sent.

• By default, the query is not printed.

+question, +noquestion This option toggles the display of the question section of a query when an answer is returned.

• The default is to print the question section as a comment.

+raflag, +noraflag This option sets [or does not set] the RA (Recursion Available) bit in the query.

• The default is +noraflag.
• This bit is ignored by the server for QUERY.

+rdflag, +nordflag This option is a synonym for +recurse, +norecurse.

+recurse, +norecurse This option toggles the setting of the RD (recursion desired) bit in the query. This bit is set by default, which means dig normally sends recursive queries.

• Recursion is automatically disabled when the +nssearch or +trace query option is used.

+retry=T This option sets the number of times to retry UDP and TCP queries to server to T instead of the default, 2. Unlike +tries, this does not include the initial query.

+rrcomments, +norrcomments This option toggles the display of per-record comments in the output (for example, human-readable key information about DNSKEY records).

• The default is not to print record comments unless multiline mode is active.

+search, +nosearch This option uses [or does not use] the search list defined by the searchlist or domain directive in resolv.conf, if any.

• The search list is not used by default.

ndots from resolv.conf (default 1), which may be overridden by +ndots, determines whether the name is treated as relative and hence whether a search is eventually performed.

+short, +noshort This option toggles whether a terse answer is provided.

• The default is to print the answer in a verbose form.
• This option always has a global effect; it cannot be set globally and then overridden on a per-lookup basis.

+showbadcookie, +noshowbadcookie This option toggles whether to show the message containing the BADCOOKIE rcode before retrying the request or not.

• The default is to not show the messages.

+showsearch, +noshowsearch This option performs [or does not perform] a search showing intermediate results.

+sigchase, +nosigchase This feature is now obsolete and has been removed; use delv instead.

+split=W This option splits long hex- or base64-formatted fields in resource records into chunks of W characters (where W is rounded up to the nearest multiple of 4). +nosplit or +split=0 causes fields not to be split at all.

• The default is 56 characters, or 44

characters when multiline mode is active.

+stats, +nostats This option toggles the printing of statistics.

• when the query was made, the size of the reply, etc.
• The default behavior is to print the query statistics as a comment after each lookup.

+subnet=addr[/prefix-length], +nosubnet This option sends [or does not send] an EDNS CLIENT-SUBNET option with the specified IP address or network prefix.

dig +subnet=0.0.0.0/0, or simply dig +subnet=0 for short, sends an EDNS CLIENT-SUBNET option with an empty address and a source prefix-length of zero, which signals a resolver that the client's address information must not be used when resolving this query.

+tcflag, +notcflag This option sets [or does not set] the TC (TrunCation) bit in the query.

• The default is

+notcflag.

• This bit is ignored by the server for QUERY.

+tcp, +notcp This option indicates whether to use TCP when querying name servers. The default behavior is to use UDP unless a type any or ixfr=N query is requested, in which case the default is TCP.

• AXFR queries always use TCP.
• To prevent retry over TCP when TC=1 is returned from a UDP query, use +ignore.

+timeout=T This option sets the timeout for a query to T seconds.

• The default timeout is 5 seconds.

An attempt to set T to less than 1 is silently set to 1.

+tls, +notls This option indicates whether to use DNS over TLS (DoT) when querying name servers.

• When this option is in use, the port number defaults to 853.

+tls-ca[=file-name], +notls-ca This option enables remote server TLS certificate validation for DNS transports, relying on TLS.

• Certificate authorities certificates are loaded from the specified PEM file

(file-name).

• If the file is not specified, the default certificates from the global certificates store are used.

+tls-certfile=file-name, +tls-keyfile=file-name, +notls-certfile, +notls-keyfile These options set the state of certificate-based client authentication for DNS transports, relying on TLS.

• Both certificate chain file and private key file are expected to be in PEM format. Both options must be specified at the same time.

+tls-hostname=hostname, +notls-hostname This option makes dig use the provided hostname during remote server TLS certificate verification.

• Otherwise, the DNS server name is used.
• This option has no effect if

+tls-ca is not specified.

+topdown, +notopdown This feature is related to dig +sigchase, which is obsolete and has been removed.

• Use delv instead.

+trace, +notrace This option toggles tracing of the delegation path from the root name servers for the name being looked up.

• Tracing is disabled by default.
• When tracing is enabled, dig makes iterative queries to resolve the name being looked up.
• It follows referrals from the root servers, showing the answer from each server that was used to resolve the lookup.

If @server is also specified, it affects only the initial query for the root zone name servers.

+dnssec is also set when +trace is set, to better emulate the default queries from a name server.

+tries=T This option sets the number of times to try UDP and TCP queries to server to T instead of the default, 3.

• If T is less than or equal to zero, the number of tries is silently rounded up to 1.

+trusted-key=#### This option formerly specified trusted keys for use with dig +sigchase.

• This feature is now obsolete and has been removed; use delv instead.

+ttlid, +nottlid This option displays [or does not display] the TTL when printing the record.

+ttlunits, +nottlunits This option displays [or does not display] the TTL in friendly human-readable time units of s, m, h, d, and w, representing seconds, minutes, hours, days, and weeks.

• This implies +ttlid.

+unknownformat, +nounknownformat This option prints all RDATA in unknown RR type presentation format (RFC 3597). The default is to print RDATA for known types in the type's presentation format.

+vc, +novc This option uses [or does not use] TCP when querying name servers.

• This alternate syntax to +tcp is provided for backwards compatibility.
• The vc stands for "virtual circuit."

+yaml, +noyaml When enabled, this option prints the responses (and, if +qr is in use, also the outgoing queries) in a detailed YAML format.

+zflag, +nozflag This option sets [or does not set] the last unassigned DNS header flag in a DNS query. This flag is off by default.

MULTIPLE QUERIES

The BIND 9 implementation of dig supports specifying multiple queries on the command line (in addition to supporting the -f batch file option).

• Each of those queries can be supplied with its own set of flags, options, and query options.

In this case, each query argument represents an individual query in the command-line syntax described above.

• Each consists of any of the standard options and flags, the name to be looked up, an optional query type and class, and any query options that should be applied to that query.

A global set of query options, which should be applied to all queries, can also be supplied. These global query options must precede the first tuple of name, class, type, options, flags, and query options supplied on the command line.

• Any global query options (except +cmd and

+short options) can be overridden by a query-specific set of query options.

• For example:

dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr

shows how dig can be used from the command line to make three lookups.

• an ANY query for www.isc.org, a reverse lookup of 127.0.0.1, and a query for the NS records of isc.org.
• A global query option of +qr is applied, so that dig shows the initial query it made for each lookup.

The final query has a local query option of +noqr which means that dig does not print the initial query when it looks up the NS records for isc.org.

IDN SUPPORT

If dig has been built with IDN (internationalized domain name) support, it can accept and display non-ASCII domain names.

• dig appropriately converts character encoding of a domain name before sending a request to a DNS server or displaying a reply from the server. To turn off

IDN support, use the parameters +idnin and +idnout, or define the IDN_DISABLE environment variable.

RETURN CODES

dig return codes are:

0 DNS response received, including NXDOMAIN status

1 Usage error

8 Couldn't open batch file

9 No reply from server

10 Internal error

FILES

/etc/resolv.conf

${HOME}/.digrc