这是域名被污染吗？

用 b 根解析 com 地址

[root@localhost ~]# dig @b.root-servers.net com

; <<>> DiG 9.9.4-RedHat-9.9.4-74.el7_6.1 <<>> @b.root-servers.net com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29150
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 13, ADDITIONAL: 27
;; WARNING: recursion requested but not available

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

;; AUTHORITY SECTION:
com.			172800	IN	NS	d.gtld-servers.net.
com.			172800	IN	NS	i.gtld-servers.net.
com.			172800	IN	NS	m.gtld-servers.net.
com.			172800	IN	NS	f.gtld-servers.net.
com.			172800	IN	NS	h.gtld-servers.net.
com.			172800	IN	NS	a.gtld-servers.net.
com.			172800	IN	NS	g.gtld-servers.net.
com.			172800	IN	NS	e.gtld-servers.net.
com.			172800	IN	NS	b.gtld-servers.net.
com.			172800	IN	NS	j.gtld-servers.net.
com.			172800	IN	NS	c.gtld-servers.net.
com.			172800	IN	NS	l.gtld-servers.net.
com.			172800	IN	NS	k.gtld-servers.net.

;; ADDITIONAL SECTION:
a.gtld-servers.net.	172800	IN	A	192.5.6.30
b.gtld-servers.net.	172800	IN	A	192.33.14.30
c.gtld-servers.net.	172800	IN	A	192.26.92.30
d.gtld-servers.net.	172800	IN	A	192.31.80.30
e.gtld-servers.net.	172800	IN	A	192.12.94.30
f.gtld-servers.net.	172800	IN	A	192.35.51.30
g.gtld-servers.net.	172800	IN	A	192.42.93.30
h.gtld-servers.net.	172800	IN	A	192.54.112.30
i.gtld-servers.net.	172800	IN	A	192.43.172.30
j.gtld-servers.net.	172800	IN	A	192.48.79.30
k.gtld-servers.net.	172800	IN	A	192.52.178.30
l.gtld-servers.net.	172800	IN	A	192.41.162.30
m.gtld-servers.net.	172800	IN	A	192.55.83.30
a.gtld-servers.net.	172800	IN	AAAA	2001:503:a83e::2:30
b.gtld-servers.net.	172800	IN	AAAA	2001:503:231d::2:30
c.gtld-servers.net.	172800	IN	AAAA	2001:503:83eb::30
d.gtld-servers.net.	172800	IN	AAAA	2001:500:856e::30
e.gtld-servers.net.	172800	IN	AAAA	2001:502:1ca1::30
f.gtld-servers.net.	172800	IN	AAAA	2001:503:d414::30
g.gtld-servers.net.	172800	IN	AAAA	2001:503:eea3::30
h.gtld-servers.net.	172800	IN	AAAA	2001:502:8cc::30
i.gtld-servers.net.	172800	IN	AAAA	2001:503:39c1::30
j.gtld-servers.net.	172800	IN	AAAA	2001:502:7094::30
k.gtld-servers.net.	172800	IN	AAAA	2001:503:d2d::30
l.gtld-servers.net.	172800	IN	AAAA	2001:500:d937::30
m.gtld-servers.net.	172800	IN	AAAA	2001:501:b1f9::30

;; Query time: 198 msec
;; SERVER: 199.9.14.201#53(199.9.14.201)
;; WHEN: Sun Aug 04 06:29:16 UTC 2019
;; MSG SIZE  rcvd: 828

还是用 b 根解析 hdb.com

[root@localhost ~]# dig @b.root-servers.net hdb.com

; <<>> DiG 9.9.4-RedHat-9.9.4-74.el7_6.1 <<>> @b.root-servers.net hdb.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 50917
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;hdb.com.			IN	A

;; ANSWER SECTION:
hdb.com.		213	IN	A	31.13.85.1

;; Query time: 27 msec
;; SERVER: 199.9.14.201#53(199.9.14.201)
;; WHEN: Sun Aug 04 06:29:06 UTC 2019
;; MSG SIZE  rcvd: 41

明显解析 hdb.com 结果是有问题的