;; connection timed out; no servers can be reached

Issue

• DNS 解析失败，并显示错误连接超时。

  # nslookup redhat.com
  ;; connection timed out; no servers could be reached
  

• 当对 /etc/hosts 中的记录执行 ping 命令，但 nslookup DNS 解析失败时。

  [root@nlams01nwbkp001v discover]# ping localhost
  PING localhost(localhost (::1)) 56 data bytes
  64 bytes from localhost (::1): icmp_seq=1 ttl=64 time=0.038 ms
  64 bytes from localhost (::1): icmp_seq=2 ttl=64 time=0.019 ms
  
  [root@node-0 ~]# nslookup localhost
  ;; connection timed out; no servers could be reached
  
  [root@node-0 ~]# nslookup myhostname.redhat.com
  ;; connection timed out; no servers could be reached