/etc/resolve.conflists the current dns server for resolving dns requests
/etc/hostsis a local list of dns entries
/etc/nsswitch.confis the config of the GNU Name Service Switch
# /etc/hosts can be used to block websites: $ echo '0.0.0.0 example.com' >> /etc/hosts
A socket contains a source and destination ip and port, it lists every connection.
Ports 0-1024 are “privilege ports” and require root to use.
Port 42 used to be used for WINS, Windows Internet Naming Service, before it was replaced with regular DNS.
Port 53 is for DNS.
HTTP is on port 80 for the server and for any port over 1024 for the client.
BIND - Berkeley Internet Naming Daemon
Zones determine which DNS server has authority, zone files determine when to use cache and when to use the zone authority.