/etc/hosts - The file responsible for resolving the host from the client-side or file-based resolution
Since this is not scalable, an external dns server can be configured.
/etc/resolv.conf - The file responsible for managing external dns entries
$ cat /etc/resolv.conf
search caleston.ca
nameserver 8.8.8.8
options ndots:5
The order of dns resolution can be configured at /etc/nsswitch.conf
$ cat /etc/nsswitch.conf
# /etc/nsswitch.conf
#
# Example configuration of GNU Name Service Switch functionality.
# If you have the `glibc-doc-reference' and `info' packages installed, try:
# `info libc "Name Service Switch"' for information about this file.
passwd: compat systemd
group: compat systemd
shadow: compat
gshadow: files
hosts: files dns
networks: files
protocols: db files
services: db files
ethers: db files
rpc: db files
netgroup: nis