Code:
# cat list.txt
server1
server2
server3
server4
# data to be compared of.
#dns address
1.1.1.1
2.2.2.2
3.3.3.3
#for i in `cat list.txt`
do
grep dns $ i
doneCode:
#cat server1|grep dns
1.2.3.4
Then it will send an email that dns is different, not equal to 1.1.1.1 , 2.2.2.2 and 3.3.3.3done,,we may clsed this