/etc/resolv.conf檔案中的search項作用-不能去掉
阿新 • • 發佈：2018-12-21
resolv.conf檔案中有search項時，主機名解析規則順序：
DNS配置檔案如下：
# vi /etc/resolv.conf
# Generated by NetworkManager
search openstack.local dev.com example.local
nameserver 192.168.122.21例1：查詢主機名，因為主機名後面沒有點，就認為是主機名，所以先新增search裡的每一項依次組成FQDN（完全合格域名）來查詢，完全合格域名查詢未找到，就再認為主機名是完全合格域名來查詢。
# host -a centos7-bind-1 Trying "centos7-bind-1.openstack.local" Trying "centos7-bind-1.dev.com" Trying "centos7-bind-1.example.local" Trying "centos7-bind-1" ;; connection timed out; no servers could be reached
例2：查詢主機名，因為主機名中有點（不是末尾有點），就認為是完全合格域名，先用它來查詢，查詢失敗就把它當成是主機名來進行，新增search裡的每一項組成FQDN（完全合格域名）來查詢。
# host -a centos7-bind-1.com Trying "centos7-bind-1.com" Received 109 bytes from 192.168.122.21#53 in 177 ms Trying "centos7-bind-1.com.openstack.local" Trying "centos7-bind-1.com.dev.com" Trying "centos7-bind-1.com.example.local" Host centos7-bind-1.com not found: 3(NXDOMAIN) Received 125 bytes from 192.168.122.21#53 in 55 ms
例3：查詢主機名，因為主機名中末尾有點，則認為是完全合格域名，只用它來查詢（不會再新增search裡的每一項）。查詢次數會與search裡項域名個數有關。
# host -a centos7-bind-1. Trying "centos7-bind-1" ;; connection timed out; trying next origin Trying "centos7-bind-1" ;; connection timed out; trying next origin Trying "centos7-bind-1" ;; connection timed out; trying next origin Trying "centos7-bind-1" ;; connection timed out; no servers could be reached
原始文章連結:https://blog.csdn.net/hxpjava1/article/details/80179235