First, We need to understand the difference and relation between the network connection and a network interface. A network interface can have many connections but one connection is only bounded to a specific network interface. Network connections are unclassified by default. It’s a system or network administrator's responsibility to create a zone with specific details to enable a level of trust by creating firewall policies. Network Zone explains the trust level of a network connection. Creating Zones helps in identifying the secure network or unsecured network. Your system can have large access in a secure zone and limited to other zones or unsecured networks. This helps Network administrators to plan the level of monitoring for different networks. The initial network zones: trusted Fully trusted connections. All the incoming traffic is allowed. home work internal Partly trusted connections. User/administrator defines open services. DMZ Mostly untrusted connections, the demilitarized zone. Public external Mostly untrusted connections. User/administrator defines the open services. block Fully untrusted connections. No incoming traffic is allowed. drop Fully untrusted connections. All packets are dropped immediately.