使用dig查詢dns解析

chenwenming

               
一般來說linux下查詢域名解析有兩種選擇，nslookup或者dig，而在使用上我覺得dig更加方便順手。
如果是在debian下的話，只要裝上dnsutils這個包就可以使用dig命令了。
最基本的使用方式就是
dig www.oolec.com
即查詢域名的A記錄，查詢的dns服務器將采用系統(tǒng)配置的服務器，即/etc/resovle.conf 中的。
如果要查詢其他類型的記錄，比如MX，CNAME，NS，PTR等，只需將類型加在命令后面即可
dig www.oolec.com mx
dig www.oolec.com ns
此外，如果你是一個系統(tǒng)管理員，部署好了一臺dns服務器之后想對它進行解析測試，就必須要顯式指定待測試的dns服務器地址了，例如
dig @202.106.0.20 www.oolec.com a
默認情況下dig將采用udp協(xié)議進行查詢，如果要采用tcp方式，可以加上 +tcp參數
dig www.oolec.com a +tcp
另外一個重要的功能是+trace參數，使用這個參數之后將顯示從根域逐級查詢的過程
dig www.oolec.com a +trace
比如，對本站域名www.linuxers.cn A記錄的trace查詢可以看到根域.，頂級域.cn，以及l(fā)inuxers.cn的域名權威服務器的地址及其各自的返回結果，這樣對于追蹤dns解析中的問題有很大的幫助。
leconte@localhost:~$ dig www.linuxers.cn a +trace

; > DiG 9.5.1-P3 > www.linuxers.cn a +trace
;; global options:  printcmd
.                       215857  IN      NS      E.ROOT-SERVERS.NET.
.                       215857  IN      NS      B.ROOT-SERVERS.NET.
.                       215857  IN      NS      J.ROOT-SERVERS.NET.
.                       215857  IN      NS      K.ROOT-SERVERS.NET.
.                       215857  IN      NS      L.ROOT-SERVERS.NET.
.                       215857  IN      NS      F.ROOT-SERVERS.NET.
.                       215857  IN      NS      G.ROOT-SERVERS.NET.
.                       215857  IN      NS      I.ROOT-SERVERS.NET.
.                       215857  IN      NS      M.ROOT-SERVERS.NET.
.                       215857  IN      NS      A.ROOT-SERVERS.NET.
.                       215857  IN      NS      C.ROOT-SERVERS.NET.
.                       215857  IN      NS      H.ROOT-SERVERS.NET.
.                       215857  IN      NS      D.ROOT-SERVERS.NET.
;; Received 228 bytes from 192.168.127.2#53(192.168.127.2) in 12 ms

cn.                     172800  IN      NS      a.dns.cn.
cn.                     172800  IN      NS      b.dns.cn.
cn.                     172800  IN      NS      c.dns.cn.
cn.                     172800  IN      NS      d.dns.cn.
cn.                     172800  IN      NS      e.dns.cn.
cn.                     172800  IN      NS      ns.cernet.net.
;; Received 298 bytes from 199.7.83.42#53(L.ROOT-SERVERS.NET) in 496 ms

linuxers.cn.            21600   IN      NS      ns1.dnspood.net.
linuxers.cn.            21600   IN      NS      ns2.dnspood.net.
;; Received 80 bytes from 202.112.0.44#53(ns.cernet.net) in 12 ms

www.linuxers.cn.        600     IN      A       218.240.42.72
;; Received 49 bytes from 222.186.26.115#53(ns2.dnspood.net) in 1132 ms

今天剛好是百度出問題時候。
關于dig的更進一步的使用方式請參考
這里
dig (1) - BIND9
(Updated: Jun 30, 2000)

NAME
dig - DNS lookup utility

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

DESCRIPTION
dig
(domain information groper) 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
digis 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. Unlike earlier versions, 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
will try each of the servers listed in
/etc/resolv.conf.
When no command line arguments or options are given,
dig
will perform 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 IN and CH class names overlap with the IN and CH top level domains names. Either use the
-t
and
-c
options to specify the type and class, use the
-q
the specify the domain name, or use "IN." and "CH." when looking up these top level domains.

SIMPLE USAGE
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
and queries the name servers listed there. 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
will perform a lookup for an A record.

OPTIONS
The
-b
option sets the source IP address of the query to
address. This must be a valid address on one of the host's
network interfaces or "0.0.0.0" or "::". An optional port may be
specified by appending "#"
The default query class (IN for internet) is overridden by the
-c
option.
class
is any valid class, such as HS for Hesiod records or CH for Chaosnet records.
The
-f
option makes
dig
operate in batch mode by reading a list of lookup requests to process from the file
filename. The file contains a number of queries, one per line.
Each entry in the file should be organized in the same way they would
be presented as queries to
dig
using the command-line interface.
The
-m
option enables memory usage debugging.
If a non-standard port number is to be queried, the
-p
option is used.
port#
is the port number that
digwill send its queries instead of the standard DNS port number
53. This option would be used to test a name server that has been
configured to listen for queries on a non-standard port number.
The
-4
option forces
dig
to only use IPv4 query transport. The
-6
option forces
dig
to only use IPv6 query transport.
The
-t
option sets the query type to
type. It can be any valid query type which is supported in BIND 9. The default query type is "A", unless the
-xoption is supplied to indicate a reverse lookup. A zone
transfer can be requested by specifying a type of AXFR. When an
incremental zone transfer (IXFR) is required,
typeis set to
ixfr=N. The incremental zone transfer will contain the changes made to
the zone since the serial number in the zone's SOA record was
N.
The
-q
option sets the query name to
name. This useful do distinguish the
name
from other arguments.
Reverse lookups --- mapping addresses to names --- are simplified by the
-x
option.
addris an IPv4 address in dotted-decimal notation, or a
colon-delimited IPv6 address. When this option is used, there is no
need to provide the
name,
class
and
type
arguments.
digautomatically performs a lookup for a name like
11.12.13.10.in-addr.arpa
and sets the query type and class to PTR and IN respectively. By
default, IPv6 addresses are looked up using nibble format under the
IP6.ARPA domain. To use the older RFC1886 method using the IP6.INT
domain specify the
-i
option. Bit string labels (RFC2874) are now experimental and are not attempted.
To sign the DNS queries sent by
dig
and their responses using transaction signatures (TSIG), specify a TSIG key file using the
-k
option. You can also specify the TSIG key itself on the command line using the
-y
option;
hmac
is the type of the TSIG, default HMAC-MD5,
name
is the name of the TSIG key and
key
is the actual key. The key is a base-64 encoded string, typically generated by

dnssec-keygen
(8). Caution should be taken when using the
-y
option on multi-user systems as the key can be visible in the output from

ps
(1)
or in the shell's history file. When using TSIG authentication with
dig, the name server that is queried needs to know the key and
algorithm that is being used. In BIND, this is done by providing
appropriate
key
and
server
statements in
named.conf.

QUERY OPTIONS
digprovides 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. The query options are:
+[no]tcp
Use [do not use] TCP when
querying name servers. The default behavior is to use UDP unless an
AXFR or IXFR query is requested, in which case a TCP connection is
used.
+[no]vc
Use [do not use] TCP when querying name servers. This alternate syntax to
+[no]tcp
is provided for backwards compatibility. The "vc" stands for "virtual circuit".
+[no]ignore
Ignore truncation in UDP responses instead of retrying with TCP. By default, TCP retries are performed.
+domain=somename
Set the search list to contain the single domain
somename, as if specified in a
domain
directive in
/etc/resolv.conf, and enable search list processing as if the
+search
option were given.
+[no]search
Use [do 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.
+[no]showsearch
Perform [do not perform] a search showing intermediate results.
+[no]defname
Deprecated, treated as a synonym for
+[no]search
+[no]aaonly
Sets the "aa" flag in the query.
+[no]aaflag
A synonym for
+[no]aaonly.
+[no]adflag
Set [do not set] the AD
(authentic data) bit in the query. The AD bit currently has a standard
meaning only in responses, not in queries, but the ability to set the
bit in the query is provided for completeness.
+[no]cdflag
Set [do not set] the CD
(checking disabled) bit in the query. This requests the server to not
perform DNSSEC validation of responses.
+[no]cl
Display [do not display] the CLASS when printing the record.
+[no]ttlid
Display [do not display] the TTL when printing the record.
+[no]recurse
Toggle 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 options are used.
+[no]nssearch
When this option is set,
digattempts 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.
+[no]trace
Toggle 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,
digmakes iterative queries to resolve the name being looked up.
It will follow referrals from the root servers, showing the answer from
each server that was used to resolve the lookup.
+[no]cmd
Toggles the printing of the initial comment in the output identifying the version of
dig
and the query options that have been applied. This comment is printed by default.
+[no]short
Provide a terse answer. The default is to print the answer in a verbose form.
+[no]identify
Show [or do not show] the IP address and port number that supplied the answer when the
+shortoption 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.
+[no]comments
Toggle the display of comment lines in the output. The default is to print comments.
+[no]stats
This query option toggles the
printing of statistics: when the query was made, the size of the reply
and so on. The default behavior is to print the query statistics.
+[no]qr
Print [do not print] the query as it is sent. By default, the query is not printed.
+[no]question
Print [do not print] the
question section of a query when an answer is returned. The default is
to print the question section as a comment.
+[no]answer
Display [do not display] the answer section of a reply. The default is to display it.
+[no]authority
Display [do not display] the authority section of a reply. The default is to display it.
+[no]additional
Display [do not display] the additional section of a reply. The default is to display it.
+[no]all
Set or clear all display flags.
+time=T
Sets the timeout for a query to
T
seconds. The default timeout is 5 seconds. An attempt to set
T
to less than 1 will result in a query timeout of 1 second being applied.
+tries=T
Sets the number of times to try UDP 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.
+retry=T
Sets the number of times to retry UDP queries to server to
T
instead of the default, 2. Unlike
+tries, this does not include the initial query.
+ndots=D
Set the number of dots that have to appear in
name
to
D
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 will be searched
for in the domains listed in the
search
or
domain
directive in
/etc/resolv.conf.
+bufsize=B
Set the UDP message buffer size advertised using EDNS0 to
Bbytes. The maximum and minimum sizes of this buffer are 65535
and 0 respectively. Values outside this range are rounded up or down
appropriately. Values other than zero will cause a EDNS query to be
sent.
+edns=#
Specify the EDNS version to query with. Valid values are 0 to 255. Setting the EDNS version will cause a EDNS query to be sent.
+noedns
clears the remembered EDNS version.
+[no]multiline
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.
+[no]fail
Do not try the next server if
you receive a SERVFAIL. The default is to not try the next server which
is the reverse of normal stub resolver behavior.
+[no]besteffort
Attempt to display the contents of messages which are malformed. The default is to not display malformed answers.
+[no]dnssec
Requests DNSSEC records be sent by setting the DNSSEC OK bit (DO) in the OPT record in the additional section of the query.
+[no]sigchase
Chase DNSSEC signature chains. Requires dig be compiled with -DDIG_SIGCHASE.
+trusted-key=####
Specifies a file containing trusted keys to be used with
+sigchase. Each DNSKEY record must be on its own line.
If not specified
dig
will look for
/etc/trusted-key.key
then
trusted-key.key
in the current directory.
Requires dig be compiled with -DDIG_SIGCHASE.
+[no]topdown
When chasing DNSSEC signature chains perform a top-down validation. Requires dig be compiled with -DDIG_SIGCHASE.
+[no]nsid
Include an EDNS name server ID request when sending a query.

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
queryargument represent 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 the
+[no]cmd
option) 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
could 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
will 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.
digappropriately converts character encoding of domain name
before sending a request to DNS server or displaying a reply from the
server. If you'd like to turn off the IDN support for some reason,
defines the
IDN_DISABLE
environment variable. The IDN support is disabled if the variable is set when
dig
runs.

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

SEE ALSO

host
(1),

named
(8),

dnssec-keygen
(8),
RFC1035.

BUGS
There are probably too many query options.

COPYRIGHT
Copyright © 2004-2008 Internet Systems Consortium, Inc. ("ISC")
Copyright © 2000-2003 Internet Software Consortium.
               
               
               
               
               

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