nslookup、host 和 dig 是三个 DNS 查询工具，以下会分别介绍它们的使用方法。
nslookup is a tried and true program that has weathered the ages. nslookup has been deprecated and may be removed from future releases. There is not even a man page for this program.
因此，这里不过多介绍。
host 命令和 dig 命令很相像，但是 host 命令的输出要更简洁，如下示例
# host www.google.com
www.google.com has address 74.125.135.106
host 命令只输出给我们 dig 命令的 ANSWER section，相对 dig 提供的一些不必要的信息来说更简洁快速。也可指定 DNS Server 来查询，例如我想使用 Google DNS 8.8.8.8,named 可以如下指定
# host www.google.com 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases:
www.google.com has address 173.194.72.147
host 反解析# host 173.194.72.147
147.72.194.173.in-addr.arpa domain name pointer tf-in-f147.1e100.net.
-t 选项# host -t SOA google.com # 查询 SOA 记录信息
google.com has SOA record ns1.google.com. dns-admin.google.com. 2013061100 7200 1800 1209600 300
MX 记录$ host -t MX google.com
google.com mail is handled by 10 aspmx.l.google.com.
google.com mail is handled by 40 alt3.aspmx.l.google.com.
google.com mail is handled by 20 alt1.aspmx.l.google.com.
google.com mail is handled by 50 alt4.aspmx.l.google.com.
google.com mail is handled by 30 alt2.aspmx.l.google.com.
-C 对比认证 DNS SOA 信息# host -C google.com
Nameserver 216.239.34.10:
google.com has SOA record ns1.google.com. dns-admin.google.com. 2013061100 7200 1800 1209600 300
Nameserver 216.239.36.10:
google.com has SOA record ns1.google.com. dns-admin.google.com. 2013061100 7200 1800 1209600 300
Nameserver 216.239.32.10:
... ...
# host -c CH -t txt version.bind 10.10.10.2
Using domain server:
Name: 10.10.10.2 # 10.10.10.2 为 DNS Server
Address: 10.10.10.2#53
Aliases:
version.bind descriptive text "9.8.1-P2"
# host
Usage: host [-aCdlriTwv] [-c class] [-N ndots] [-t type] [-W time]
[-R number] [-m flag] hostname [server]
-a is equivalent to -v -t ANY
-c specifies query class for non-IN data # 搜索非网络数据时要指定要查找的类
-C compares SOA records on authoritative nameservers
-d is equivalent to -v
-l lists all hosts in a domain, using AXFR
-i IP6.INT reverse lookups
-N changes the number of dots allowed before root lookup is done
-r disables recursive processing
-R specifies number of retries for UDP packets
-s a SERVFAIL response should stop query
-t specifies the query type # 指定要查询的记录类型
-T enables TCP/IP mode
-v enables verbose output # 输出更详细的信息
-w specifies to wait forever for a reply
-W specifies how long to wait for a reply
-4 use IPv4 query transport only
-6 use IPv6 query transport only
-m set memory debugging flag (trace|record|usage)
dig 也是一个很强大的命令，相对 host 来说输出较为繁杂，如下：
$ dig www.google.com
... ...
;; ANSWER SECTION:
www.google.com. 297 IN A 74.125.135.106
www.google.com. 297 IN A 74.125.135.104
... ...
;; AUTHORITY SECTION:
google.com. 172796 IN NS ns3.google.com.
google.com. 172796 IN NS ns1.google.com.
google.com. 172796 IN NS ns4.google.com.
google.com. 172796 IN NS ns2.google.com.
... ...
MX 记录$ dig google.com MX | grep '^;; ANSWER SECTION:' -A 5
;; ANSWER SECTION:
google.com. 368 IN MX 50 alt4.aspmx.l.google.com.
google.com. 368 IN MX 40 alt3.aspmx.l.google.com.
google.com. 368 IN MX 10 aspmx.l.google.com.
google.com. 368 IN MX 30 alt2.aspmx.l.google.com.
google.com. 368 IN MX 20 alt1.aspmx.l.google.com.
SOA 记录$ dig google.com SOA | grep '^;; ANSWER SECTION:' -A 1
;; ANSWER SECTION:
google.com. 85539 IN SOA ns1.google.com. dns-admin.google.com. 2013061100 7200 1800 1209600 300
$ dig www.baidu.com @8.8.8.8
... ...
;; ANSWER SECTION:
www.baidu.com. 1024 IN CNAME www.a.shifen.com.
www.a.shifen.com. 166 IN A 119.75.217.56
www.a.shifen.com. 166 IN A 119.75.218.77
... ...
dig 查询版本号$ dig chaos txt version.bind 10.10.10.2 | grep '^;; ANSWER SECTION:' -A 1
;; ANSWER SECTION:
version.bind. 0 CH TXT "9.8.1-P2"
dig 反解析 -x$ dig -x 74.125.135.105
;; QUESTION SECTION:
;105.135.125.74.in-addr.arpa. IN PTR
;; ANSWER SECTION:
105.135.125.74.in-addr.arpa. 83205 IN PTR ni-in-f105.1e100.net.
dig 全过程 +trace$ dig +trace www.google.com
nslookup、host和dig 是三个DNS查询工具，以下会分别介绍它们的使用方法。