Here's something I threw together to make sure the /etc/resolv.conf
points to a working nameserver. I run this once a minute. It checks to
see what name servers are up and creates /etc/resolv.conf. As you all
know SA and mail servers need the first nameserver to always be working.
#!/bin/bash
# This program is run once a minute and automatically generates the
/etc/resolv.conf file
DEFAULTSERVERS="65.49.42.30 65.49.42.31 65.49.42.33 69.50.231.141"
# If default isn't optimum then read /etc/sysconfig/local-servers for list
[ -f /etc/sysconfig/local-nameservers ] && .
/etc/sysconfig/local-nameservers
echo "# Automatically generated by $0" > /etc/resolv.tmp
echo >> /etc/resolv.tmp
echo "domain ctyme.com" >> /etc/resolv.tmp
echo >> /etc/resolv.tmp
for ns in $LOCALNAMESERVERS $DEFAULTSERVERS; do
/usr/bin/nc -w 3 -z $ns 53 | cut -d \ -f 3 | sed -e
's/^.*$/nameserver \0/' >> /etc/resolv.tmp
done
# resolv.conf only allows 3 nameservers so truncate list to 7 lines
head -n 7 /etc/resolv.tmp > /etc/resolv.conf
rm /etc/resolv.tmp
