why EC2 /etc/resolv.conf is always got empty, and rebooting the instance can fill the values, but later on it will be empty again

Question

Does anyone know the reason why the /etc/resolv.conf is got empty at sometimes and rebooting the instance, it can fill correct values into it, but after a while, it will be empty again, all the instances created by the same AMI have this issue.

the instances are under a VPC , and we have enabled DNS resolution and DNS hostnames , and even ClassicLink DNS Support .

and running dhcpclient doesn't work.

Can someone help? Thanks

Answer 1

It turns out to be the full disk issue, I have run out of disk space, so the dhcpclient cannot write content to the resolve.conf file, and if I reboot the instance then it got a little disk space, and dns resolution works fine, but after a while, it stops working because of no disk space.

Thanks.