存在记录，AAAA 返回 SERVFAIL，主机具有双栈连接
$ host www.fidelityrewards.com
www.fidelityrewards.com has address 170.135.184.45
Host www.fidelityrewards.com not found: 2(SERVFAIL)
Ubuntu 16.10 无法通过 IPv4 连接
$ wget www.fidelityrewards.com
--2017-02-27 07:41:57-- http://www.fidelityrewards.com/
Resolving www.fidelityrewards.com (www.fidelityrewards.com)... failed: Name or service not known.
wget: unable to resolve host address ‘www.fidelityrewards.com
在双栈 Debian 8.7 上正常工作
$ wget www.fidelityrewards.com
--2017-02-27 08:44:47-- http://www.fidelityrewards.com/
Resolving www.fidelityrewards.com (www.fidelityrewards.com)... 170.135.184.45
Connecting to www.fidelityrewards.com (www.fidelityrewards.com)|170.135.184.45|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 2363 (2.3K) [text/html]
Saving to: ‘index.html.1’
index.html.1 100%[=========================>] 2.31K --.-KB/s in 0s
2017-02-27 08:44:50 (143 MB/s) - ‘index.html.1’ saved [2363/2363]
我应该针对哪个组件提交错误？glibc？
编辑：/etc/nsswitch.conf
hosts: files myhostname mdns4_minimal [NOTFOUND=return] resolve [!UNAVAIL=return] dns wins
networks: files