我用VMware安装了CentOS 7，配置了网络NAT，设置了静态IP地址，用了几天都没问题，今天发现一个名字解析问题：
$ ping www.bing.com
ping: www.bing.com: Temporary failure in name resolution
$ ping 202.89.233.101
PING 202.89.233.101 (202.89.233.101) 56(84) bytes of data.
64 bytes from 202.89.233.101: icmp_seq=1 ttl=128 time=49.1 ms
那么这是 DNS 解析问题吗？我像许多人说的那样检查了配置：
$ cat /etc/resolv.conf
nameserver 114.114.114.114
nameserver 8.8.8.8
$ cat network-scripts/ifcfg-ens33
TYPE="Ethernet"
PROXY_METHOD="none"
BROWSER_ONLY="no"
BOOTPROTO="static"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
IPV6_ADDR_GEN_MODE="stable-privacy"
NAME="ens33"
UUID="62535cbf-5ffc-40d7-8a7e-b5600a36811e"
DEVICE="ens33"
ONBOOT="yes"
IPADDR=192.168.128.200
GATEWAY=192.168.128.2
NETMASK=255.255.255.0
DNS1=114.114.114.114
DNS2=8.8.8.8
$ route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.128.2 0.0.0.0 UG 100 0 0 ens33
192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
192.168.128.0 0.0.0.0 255.255.255.0 U 100 0 0 ens33
$ cat /etc/nsswitch.conf
hosts: files dns
$ nslookup www.bing.com
;; connection timed out; trying next origin
;; connection timed out; no servers could be reached
$ iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT udp -- anywhere anywhere udp dpt:domain
ACCEPT tcp -- anywhere anywhere tcp dpt:domain
ACCEPT udp -- anywhere anywhere udp dpt:bootps
ACCEPT tcp -- anywhere anywhere tcp dpt:bootps
Chain FORWARD (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere 192.168.122.0/24 ctstate RELATED,ESTABLISHED
ACCEPT all -- 192.168.122.0/24 anywhere
ACCEPT all -- anywhere anywhere
REJECT all -- anywhere anywhere reject-with icmp-port-unreachable
REJECT all -- anywhere anywhere reject-with icmp-port-unreachable
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ACCEPT udp -- anywhere anywhere udp dpt:bootpc
$ dig @8.8.8.8 www.bing.com
; <<>> DiG 9.9.4-RedHat-9.9.4-51.el7_4.2 <<>> @8.8.8.8 www.bing.com
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
我已经重新启动了 CentOS，但它仍然不起作用。