To learn more about the various syntax used in sudoers file follow below link
There is a parameter NOPASSWD which has to be used for your user to run allowed commands without providing their password everytime.
I want to all all the user of admin group to run bind services
# visudo %admin ALL=(ALL) NOPASSWD: /etc/init.d/named reload
Verify the changes. Login as deepak and try to run the command
# su - deepak [deepak@test2 ~]$ sudo /etc/init.d/named reload Reloading named: [ OK ]
Now as we see it didn't prompted for password.
Just to allow a single user make the below changes
deepak ALL=(ALL) NOPASSWD: /etc/init.d/named reload
Allow the user to run all commands without getting prompted for password
deepak ALL=(ALL) NOPASSWD: ALL
I hope I made myself clear
How to give normal user root privileges using sudo in Linux/Unix