10.19 dig：域名查询工具
10.19.1 命令详解
【命令星级】 ★★★★☆
【功能说明】
dig命令是常用的域名查询工具，可以用于测试域名系统的工作是否正常。
【语法格式】
dig [option]
dig [选项]
**说明：**在dig命令及后面的选项里，每个元素直接都至少要有一个空格。
【选项说明】
表10-20针对该命令的参数选项进行了说明。
表10-20 dig命令的参数选项及说明
10.19.2 使用范例
**范例10-67：**查询指定域名的IP地址。
[root@centos7 ~]# dig www.baidu.com
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> www.baidu.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32999
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;www.baidu.com. IN A
;; ANSWER SECTION:
www.baidu.com. 144 IN CNAME www.a.shifen.com.
www.a.shifen.com. 144 IN A 14.215.177.39
www.a.shifen.com. 144 IN A 14.215.177.38 #查询结果。
;; Query time: 20 msec #查询时间。
;; SERVER: 223.5.5.5#53(223.5.5.5) #使用默认的DNS服务器。
;; WHEN: Sat Oct 31 16:14:16 CST 2020
;; MSG SIZE rcvd: 90
[root@centos7 ~]# dig @61.134.1.5 www.baidu.com #使用@指定查询的DNS服务器。
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> @61.134.1.5 www.baidu.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 26272
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;www.baidu.com. IN A
;; ANSWER SECTION:
www.baidu.com. 160 IN CNAME www.a.shifen.com.
www.a.shifen.com. 43 IN A 14.215.177.38
www.a.shifen.com. 43 IN A 14.215.177.39
;; Query time: 6 msec
;; SERVER: 61.134.1.5#53(61.134.1.5) #指定的DNS服务器。
;; WHEN: Sat Oct 31 16:15:44 CST 2020
;; MSG SIZE rcvd: 90
**范例10-68：**反向域名解析例子。
完整的域名解析包括正向解析（即范例10-67，将域名解析成IP地址）和反向解析（给定IP地址查询其对应的域名信息）。
[root@centos7 ~]# dig -x 101.200.195.98 #使用-x选项进行域名反向解析。
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> -x 101.200.195.98
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 28633
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;98.195.200.101.in-addr.arpa. IN PTR
;; AUTHORITY SECTION:
200.101.in-addr.arpa. 300 IN SOA rdns1.alidns.com. dnsmgr.alibaba-inc.com. 2015011388 1800 600 1814400 300
;; Query time: 82 msec
;; SERVER: 223.5.5.5#53(223.5.5.5)
;; WHEN: Sat Oct 31 16:18:32 CST 2020
;; MSG SIZE rcvd: 116
**范例10-69：**查询MX类型的域名信息。
[root@centos7 ~]# dig -t MX www.baidu.com #使用-t选项选择查询的类型。
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> -t MX www.baidu.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62124
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;www.baidu.com. IN MX
;; ANSWER SECTION:
www.baidu.com. 204 IN CNAME www.a.shifen.com.
;; AUTHORITY SECTION:
a.shifen.com. 204 IN SOA ns1.a.shifen.com. baidu_dns_master.baidu.com. 2010310002 5 5 2592000 3600
;; Query time: 35 msec
;; SERVER: 223.5.5.5#53(223.5.5.5)
;; WHEN: Sat Oct 31 16:20:24 CST 2020
;; MSG SIZE rcvd: 115
**范例10-70：**显示完整的DNS解析过程。
[root@centos7 ~]# dig @61.134.1.5 www.baidu.com +trace #显示域名解析成IP的完整过程。
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> @61.134.1.5 www.baidu.com +trace
; (1 server found)
;; global options: +cmd #显示全球13个根服务器a~m。
. 459521 IN NS h.root-servers.net.
. 459521 IN NS j.root-servers.net.
. 459521 IN NS m.root-servers.net.
. 459521 IN NS b.root-servers.net.
. 459521 IN NS c.root-servers.net.
. 459521 IN NS i.root-servers.net.
. 459521 IN NS d.root-servers.net.
. 459521 IN NS f.root-servers.net.
. 459521 IN NS g.root-servers.net.
. 459521 IN NS e.root-servers.net.
. 459521 IN NS a.root-servers.net.
. 459521 IN NS l.root-servers.net.
. 459521 IN NS k.root-servers.net.
;; Received 492 bytes from 61.134.1.5#53(61.134.1.5) in 14 ms
com. 172800 IN NS a.gtld-servers.net.
com. 172800 IN NS b.gtld-servers.net.
com. 172800 IN NS c.gtld-servers.net.
com. 172800 IN NS d.gtld-servers.net.
com. 172800 IN NS e.gtld-servers.net.
com. 172800 IN NS f.gtld-servers.net.
com. 172800 IN NS g.gtld-servers.net.
com. 172800 IN NS h.gtld-servers.net.
com. 172800 IN NS i.gtld-servers.net.
com. 172800 IN NS j.gtld-servers.net.
com. 172800 IN NS k.gtld-servers.net.
com. 172800 IN NS l.gtld-servers.net.
com. 172800 IN NS m.gtld-servers.net.
com. 86400 IN DS 30909 8 2 E2D3C916F6DEEAC73294E8268FB5885044A833FC5459588F4A9184CF C41A5766
com. 86400 IN RRSIG DS 8 1 86400 20201113050000 20201031040000 26116 . XpkdZo2GDTigjfOCUkaNxiuzisIADyBLoAF5+a9fR5J9Vb/8ysd22JFI ylK1eSq3E6yWGcMb0EsLFH1PgwIBvkxdKk/jD/jm27W3IVXdEAb6bw5J QQXfGo0cTCB4rfvA/0qAsgkigNyyNub5fOiCqZ7qeO7f1HJ3ge6esjFd UGppaU+tbm6Gjtkt7UPAVzzabOy9BgT8ucvS0HWTvhTtIlTqsrlAeZYR mf3PP9WNssMqMAS1qu9ThVY/DInJEYrof5JTUsFQ8zMFUgEiYllXu4We Ru2qDC21cFrMmf20H7mbsU+9g2THMkZGFVa8EUbvAy5FJ9g2ycLop3WN NiL/iA==
;; Received 1173 bytes from 193.0.14.129#53(k.root-servers.net) in 38 ms
baidu.com. 172800 IN NS ns2.baidu.com.
baidu.com. 172800 IN NS ns3.baidu.com.
baidu.com. 172800 IN NS ns4.baidu.com.
baidu.com. 172800 IN NS ns1.baidu.com.
baidu.com. 172800 IN NS ns7.baidu.com.
CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN NSEC3 1 1 0 - CK0Q1GIN43N1ARRC9OSM6QPQR81H5M9A NS SOA RRSIG DNSKEY NSEC3PARAM
CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN RRSIG NSEC3 8 2 86400 20201105054059 20201029033059 31510 com. b0YVi1iceOONn1fbVUF1Rsr4nHCMPBX2wFQ0i3gQUrwHy+lAPpZG8Jyo rlml77TQDLPRpxGTYDOTSMLsEphKOg049PYapmeb50UIZI3RpMGRiF68 KT5Tz3wVZ0/VQ+/krwh4ZAet3n0e5LKfZ47OPQKzc+Khu9ZvDdVmJn4K Apsa24X7CYegly6CoYcCBO20BTlmFf5AoPmuxgu9vbLg9Q==
HPVUSBDNI26UDNIV6R0SV14GC3KGR4JP.com. 86400 IN NSEC3 1 1 0 - HPVVN3Q5E5GOQP2QFE2LEM4SVB9C0SJ6 NS DS RRSIG
HPVUSBDNI26UDNIV6R0SV14GC3KGR4JP.com. 86400 IN RRSIG NSEC3 8 2 86400 20201105073106 20201029052106 31510 com. HBsF0yClb21M/d8xeTlYX4boPcqr12xL//dRIAorCnTneRgEaFmHdZVa 7J6QpkFlu842YlMeIqMJIveVMFZuKqwBNhlODTWdhNoH5b09ZUmOzliT P2QoWBzzttAf/JH9b1df5/4hOBUoLU6J1kAZcxUR7bUX2bcZwmfCEr7Y K8pkoJvU1UGR5CNmUJyL7x+P6GHdeZ/IuX9Nl0BPwoeijQ==
;; Received 761 bytes from 192.5.6.30#53(a.gtld-servers.net) in 193 ms
www.baidu.com. 1200 IN CNAME www.a.shifen.com.
a.shifen.com. 1200 IN NS ns3.a.shifen.com.
a.shifen.com. 1200 IN NS ns1.a.shifen.com.
a.shifen.com. 1200 IN NS ns4.a.shifen.com.
a.shifen.com. 1200 IN NS ns5.a.shifen.com.
a.shifen.com. 1200 IN NS ns2.a.shifen.com.
;; Received 239 bytes from 180.76.76.92#53(ns7.baidu.com) in 28 ms
**范例10-71：**精简输出例子。
[root@centos7 ~]# dig +nocmd +nocomment +nostat www.baidu.com #精简一些说明信息。
;www.baidu.com. IN A
www.baidu.com. 86 IN CNAME www.a.shifen.com.
www.a.shifen.com. 86 IN A 14.215.177.39
www.a.shifen.com. 86 IN A 14.215.177.38
10.20 host：域名查询工具
10.20.1 命令详解
【命令星级】 ★★★★☆
【功能说明】
host命令是用于查询DNS的工具，它可以将指定主机名称转换为IP地址。
【语法格式】
host [option]
host [选项]
**说明：**在host命令及后面的选项里，每个元素直接都至少要有一个空格。
【选项说明】
表10-21针对该命令的参数选项进行了说明。
表10-21 host命令的参数选项及说明
10.20.2 使用范例
**范例10-72：**DNS查询。
[root@centos7 ~]# host www.baidu.com #host命令直接接域名就可以了。
www.baidu.com is an alias for www.a.shifen.com.
www.a.shifen.com has address 14.215.177.39
www.a.shifen.com has address 14.215.177.38
**范例10-73：**查询详细信息。
[root@centos7 ~]# host -a www.baidu.com #使用-a选项查询详细信息。
Trying "www.baidu.com"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17740
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;www.baidu.com. IN ANY
;; ANSWER SECTION:
www.baidu.com. 870 IN CNAME www.a.shifen.com.
Received 58 bytes from 223.5.5.5#53 in 32 ms
范例10-74：指定DNS服务器查询。
[root@centos7 ~]# host -a www.baidu.com 61.134.1.5 #直接接指定的DNS服务器IP。
Trying "www.baidu.com"
Using domain server:
Name: 61.134.1.5
Address: 61.134.1.5#53
Aliases:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29533
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;www.baidu.com. IN ANY
;; ANSWER SECTION:
www.baidu.com. 1 IN CNAME www.a.shifen.com.
Received 58 bytes from 61.134.1.5#53 in 10 ms
**范例10-75：**按类进行查询。
[root@centos7 ~]# host -t MX www.baidu.com #使用-t选项选择查询类型。
www.baidu.com is an alias for www.a.shifen.com.