> 127.0.0.1 is used for loopback address and also for local testing purposes.Loopback means looping to our own systems, checking our own systems. It is used to test whether TCP/IP stack is correctly installed.
> MAC address stands for Media Access Control address. This is an address of a device which is identified as the Media Access Control Layer in the network architecture. The MAC address is unique and usually stored in ROM.
> It is an electronic down bridge which is used to enhance the security of a network. It's configuration has two components. i)Two routers ii)Application gateway the packets traveling through the LAN are inspected here and packets meeting certain criteria are forwarded and others are dropped