Could not resolve host: mirrorlist.centos.org Centos 7
Could not resolve host: mirrorlist.centos.org; Unknown error
This indicates that you either (a) don't have a properly configured DNS server or (b) your network configuration isn't correct and you can't connect to a DNS server to check the hostname
ping 18.104.22.168. If this fails, try
ping <local-gateway-ip>. If that also fails, your local network configuration is wrong and you'll have to check the configuration.
If you can ping
22.214.171.124, try using
dig to check the DNS settings like
host google.com or
dig google.com. If these fail, you need to check your DNS settings. Check
/etc/resolv.conf to see what's configured.
/etc/resolv.conf is blank, you need to setup a DNS resolver. I would suggest entering the following into the file using
vi (or whatever your comfortable using):
Save this file, then try
yum update again.
You can also try other DNS hosts if you would rather, such as
126.96.36.199 or any of the OpenDNS hosts.
You may have a connectivity issue somewhere, here a small process to check where you have an issue.
Check if the server has internet (ip address and correct route - if not working, check with
ip address if you have an IP address).
Check what are the resolver and ping them
You should have line with
nameserver and an IP address. Check that IP is answering.
Then do an nslookup
It should return a list of IP addresses. If not, your DNS server might not working correctly, you can try another server with
> server 188.8.131.52
And check this time it's working as expected.