linux命令--dig

dig，和nslookup作用有些类似，都是DNS查询工具，但是却比nslookup强大

dig，其实是一个缩写，即Domain Information Groper。

【我想用google-DNS来查baidu.com的A记录】

wangkongming@Vostro ~ $ dig @8.8.8.8 www.baidu.com A

; <<>> DiG 9.9.-3ubuntu0.-Ubuntu <<>> @8.8.8.8 www.baidu.com A
; ( server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id:
;; flags: qr rd ra; QUERY: , ANSWER: , AUTHORITY: , ADDITIONAL: 

;; OPT PSEUDOSECTION:
; EDNS: version: , flags:; udp:
;; QUESTION SECTION:
;www.baidu.com.            IN    A

;; ANSWER SECTION:
www.baidu.com.            IN    CNAME    www.a.shifen.com.
www.a.shifen.com.        IN    A    220.181.111.188
www.a.shifen.com.        IN    A    220.181.112.244

;; Query time:  msec
;; SERVER: 8.8.8.8#(8.8.8.8)
;; WHEN: Fri Sep  :: CST
;; MSG SIZE  rcvd: 

【跟踪dig全过程】

wangkongming@Vostro ~ $ dig +trace www.baidu.com

; <<>> DiG 9.9.-3ubuntu0.-Ubuntu <<>> +trace www.baidu.com
;; global options: +cmd
.                IN    NS    d.root-servers.net.
.                IN    NS    g.root-servers.net.
.                IN    NS    k.root-servers.net.
.                IN    NS    e.root-servers.net.
.                IN    NS    l.root-servers.net.
.                IN    NS    m.root-servers.net.
.                IN    NS    i.root-servers.net.
.                IN    NS    a.root-servers.net.
.                IN    NS    f.root-servers.net.
.                IN    NS    h.root-servers.net.
.                IN    NS    c.root-servers.net.
.                IN    NS    j.root-servers.net.
.                IN    NS    b.root-servers.net.
;; Received  bytes from 127.0.1.1#(127.0.1.1) in  ms

com.                IN    NS    a.gtld-servers.net.
com.                IN    NS    b.gtld-servers.net.
com.                IN    NS    c.gtld-servers.net.
com.                IN    NS    d.gtld-servers.net.
com.                IN    NS    e.gtld-servers.net.
com.                IN    NS    f.gtld-servers.net.
com.                IN    NS    g.gtld-servers.net.
com.                IN    NS    h.gtld-servers.net.
com.                IN    NS    i.gtld-servers.net.
com.                IN    NS    j.gtld-servers.net.
com.                IN    NS    k.gtld-servers.net.
com.                IN    NS    l.gtld-servers.net.
com.                IN    NS    m.gtld-servers.net.
com.                IN    DS       E2D3C916F6DEEAC73294E8268FB5885044A833FC5459588F4A9184CF C41A5766
com.                IN    RRSIG    DS       . BF33r0rrYVfJvYYYCBD0stzm5pDjCBxNIQeGHyduK4Xku56XLs4MRfXc 44HpmzuWvBU4IOKRVXbjh236Eh3rbARbxYIqHx5sKFKI6KVZg0d6K8+ xTbBCJkpaUAXxoE9lz2mOFEdON/cSxAQyKyT+A/ZLPkZw8QpnaQgn2Nw qYM=
;; Received  bytes from 199.7.83.42#(l.root-servers.net) in  ms

baidu.com.            IN    NS    dns.baidu.com.
baidu.com.            IN    NS    ns2.baidu.com.
baidu.com.            IN    NS    ns3.baidu.com.
baidu.com.            IN    NS    ns4.baidu.com.
baidu.com.            IN    NS    ns7.baidu.com.
CK0POJMG874LJREF7EFN8430QVIT8BSM.com.  IN NSEC3    - CK0Q1GIN43N1ARRC9OSM6QPQR81H5M9A NS SOA RRSIG DNSKEY NSEC3PARAM
CK0POJMG874LJREF7EFN8430QVIT8BSM.com.  IN RRSIG NSEC3       com. PSL/fLCxFV7fdwY4LWjH/vcj7S7legHC05t1lEnb2sKGmXrUqoe3RZVg 9iWUm6aWxwCuEBre8s/fJzyDfYImR2fE6YB5p+GCouWkkSaxZKjNGLDa W01HoGoHOAnS1BOF6DdwODGgVuPGtx3KtB1AIKjQI2VXhOcaIAmE16hs OZQ=
HPVV2B5N85O7HJJRB7690IB5UVF9O9UA.com.  IN NSEC3    - HPVV9UNFR23OVV2EH3NNTJ1A7JE3ETFH NS DS RRSIG
HPVV2B5N85O7HJJRB7690IB5UVF9O9UA.com.  IN RRSIG NSEC3       com. cNpdZgm+VNI2KKPP6CsWTm4gSzR4AlvkjrdzTr8csBNTbFfhQMQ2S6wE m4hRe/AqkuefUEg3Df7aSwgcNMnDZm/SxU9PVpVYzuWqrdA+JU+jkd60 8S0xzxQBOQ9jkoHU9LzJb5SyuwT5BMbt0ty2h7LztvLhd7JfkrQPDnby Two=
;; Received  bytes from 192.26.92.30#(c.gtld-servers.net) in  ms

www.baidu.com.            IN    CNAME    www.a.shifen.com.
a.shifen.com.            IN    NS    ns3.a.shifen.com.
a.shifen.com.            IN    NS    ns2.a.shifen.com.
a.shifen.com.            IN    NS    ns5.a.shifen.com.
a.shifen.com.            IN    NS    ns4.a.shifen.com.
a.shifen.com.            IN    NS    ns1.a.shifen.com.
;; Received  bytes from 119.75.219.82#(ns7.baidu.com) in  ms

wangkongming@Vostro ~ $ 

【精简dig输出】

1 使用+nocmd的话，可以节省输出dig版本信息。

2 使用+short的话，仅会输出最精简的CNAME信息和A记录，其他都不会输出。就像这样：

wangkongming@Vostro ~ $ dig +short www.baidu.com
www.a.shifen.com.
180.97.33.108
180.97.33.107

3 使用+nocomment的话，可以节省输出dig的详情注释信息。

4 使用+nostat的话，最后的统计信息也不会输出。当+nocmd、+nocomment和+nostat都是用上，是这样：

wangkongming@Vostro ~ $ dig +nocmd +nocomment +nostat www.baidu.com
;www.baidu.com.            IN    A
www.baidu.com.            IN    CNAME    www.a.shifen.com.
www.a.shifen.com.        IN    A    180.97.33.108
www.a.shifen.com.        IN    A    180.97.33.107

参考文章：http://roclinux.cn/?p=2449