Normally you could add the DNS directly in the file /etc/sysconfig/docker, if you don't do that, your docker container could ping an IP, but never do the domain name translation. This is the dns of opendns, but you could change them.
+
+
# cat /etc/sysconfig/docker
+
+
# /etc/sysconfig/docker
+
#
+
# Other arguments to pass to the docker daemon process
+
# These will be parsed by the sysv initscript and appended