[email protected]:~$ host www.baidu.com
www.baidu.com is an alias for www.a.shifen.com.
www.a.shifen.com has address 115.239.211.112
www.a.shifen.com has address 115.239.210.27
[email protected]:~$ 
[email protected]:~$ 
[email protected]:~$ 
[email protected]:~$ nslookup www.baidu.com
Server:         183.60.83.19
Address:        183.60.83.19#53

Non-authoritative answer:
www.baidu.com   canonical name = www.a.shifen.com.
Name:   www.a.shifen.com
Address: 115.239.210.27
Name:   www.a.shifen.com
Address: 115.239.211.112

 
[email protected]:~$ 
[email protected]:~$ 
[email protected]:~$ 
[email protected]:~$ dig www.baidu.com

; <<>> DiG 9.10.3-P4-Ubuntu <<>> www.baidu.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 21805
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

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

;; ANSWER SECTION:
www.baidu.com.          123     IN      CNAME   www.a.shifen.com.
www.a.shifen.com.       286     IN      A       115.239.211.112
www.a.shifen.com.       286     IN      A       115.239.210.27

;; Query time: 1 msec
;; SERVER: 183.60.83.19#53(183.60.83.19)
;; WHEN: Tue Oct 23 18:58:16 CST 2018
;; MSG SIZE  rcvd: 101

 
[email protected]:~$ 
[email protected]:~$ 
[email protected]:~$ 
[email protected]:~$ dig @8.8.8.8 www.baidu.com

; <<>> DiG 9.10.3-P4-Ubuntu <<>> @8.8.8.8 www.baidu.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9526
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;www.baidu.com.                 IN      A

;; ANSWER SECTION:
www.baidu.com.          1067    IN      CNAME   www.a.shifen.com.
www.a.shifen.com.       299     IN      A       115.239.211.112
www.a.shifen.com.       299     IN      A       115.239.210.27

;; Query time: 88 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Tue Oct 23 18:58:36 CST 2018
;; MSG SIZE  rcvd: 101

 
[email protected]:~$ 

          注意下那個Query time, 其餘的不多說。