ubuntu manually set dns resolution

After setting dns in /etc/resolv.conf, the file will be overwritten every time Ubuntu Server is restarted. For this situation, we have found some solutions. Methods
to prevent /etc/resolv.conf from being overwritten
[Method 1]
1. Required Create a file /etc/resolvconf/resolv.conf.d/tail

sudo vi /etc/resolvconf/resolv.conf.d/tail

2. Write the dns server you need in this file, the format is the same as /etc/resolv.conf

nameserver 8.8.8.8 

3. Restart the resolvconf program

sudo /etc/init.d/resolvconf restart 

Go to the /etc/resolv.conf file again, you can see that the dns server you added has been added to the file
[method 2]
in /etc/network/interfaces

###interfaces中#######     
auto eth0     
iface eth0 inet static     
address 192.168.3.250     
netmask 255.255.255.0 #subnet mask     
gateway 192.168.3.1 #gateway     
dns-nameservers 8.8.8.8 8.8.4.4 #Set up dns server  

Reference: [url] http://www.linuxidc.com/Linux/2012-06/63054.htm [/ url]