dig查看DNS递归解析的过程

[albert@node3 ~]$ dig www.albert.com

; <<>> DiG 9.9.4-RedHat-9.9.4-61.el7_5.1 <<>> www.albert.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 21564
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.albert.com.                        IN      A

;; ANSWER SECTION:
www.albert.com.         18      IN      A       172.16.9.100

;; AUTHORITY SECTION:
com.                    69158   IN      NS      a.tl-server.net.

;; ADDITIONAL SECTION:
a.tl-server.net.        69466   IN      A       192.168.56.101

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Nov 23 15:46:26 CST 2018
;; MSG SIZE  rcvd: 104

[albert@node3 ~]$ dig www.albert.com +trace

; <<>> DiG 9.9.4-RedHat-9.9.4-61.el7_5.1 <<>> www.albert.com +trace
;; global options: +cmd
.                       69113   IN      NS      a.root-server.net.
;; Received 74 bytes from 127.0.0.1#53(127.0.0.1) in 2 ms
# 从本机(127.0.0.1#53)的bind中找到根域的DNS server，开始递归

com.                    86400   IN      NS      a.tl-server.net.
;; Received 88 bytes from 192.168.56.100#53(a.root-server.net) in 2 ms
# 从根域的DNS server(192.168.56.100#53)查询顶级域名.com的DNS server

albert.com.             86400   IN      NS      ns1.albert.com.
;; Received 77 bytes from 192.168.56.101#53(a.tl-server.net) in 4 ms
# 从.com权威DNS server(192.168.56.101#53)查询albert.com的权威DNS server

www.albert.com.         60      IN      A       172.16.9.100
albert.com.             30      IN      NS      ns1.albert.com.
;; Received 93 bytes from 192.168.56.102#53(ns1.albert.com) in 0 ms
# 从albert.com权威DNS server(192.168.56.102#53)负责解析www.albert.com

[albert@node3 ~]$ dig www.albert.com -t soa

; <<>> DiG 9.9.4-RedHat-9.9.4-61.el7_5.1 <<>> www.albert.com -t soa
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60986
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.albert.com.                        IN      SOA

;; AUTHORITY SECTION:
albert.com.             30      IN      SOA     ns1.albert.com. mail.albert.com. 2018112301 30 3600 30 10800

;; Query time: 1 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Nov 23 15:46:38 CST 2018
;; MSG SIZE  rcvd: 88