77
Firewall:
A firewall is a method of implementing common as well as user defined security policies in an
effort to keep intruders out. Firewalls work by analyzing and filtering out IP packets that violate a set of rules
defined by the firewall administrator. The firewall is located at the point of entry for the network. All data
inbound and outbound must pass through the firewall for inspection.
Full Duplex:
Data transmission can be transmitted and received on the same signal medium and at the
same time. Full Duplex lines are bidirectional.
Half Duplex:
Data transmission can be transmitted and received on the same signal medium, but not
simultaneously. Half Duplex lines are bidirectional.
Host:
In context of Internet Protocol, a host computer is one that has full two way access to other computers
on the Internet.
IP:
Internet Protocol: The method by which information is sent from one computer to another through the
Internet. Each of these host computers have a unique IP address which distinguishes it from all the other
computers on the internet. Each packet of data sent includes the sender’s IP address and the receiver’s IP
address.
LAN:
Local Area Network: A group of computers, typically covering a small geographic area, that share
devices such as printers, hard disk drives, scanners, and optical drives. Computers in a LAN typically share
an internet connection through some sort of router that connects the computers to a WAN.
MAC Address:
Media Access Control Address: A unique hardware number on a computer or device that
identifies it and relates it to the IP address of that device.
MC:
Multicast: Communication involving a single sender and multiple specific receivers in a network.
MTU:
Maximum Transmission Unit: The largest size packet that can be sent by the modem. If the network
stack of any packet is larger than the MTU value, then the packet will be fragmented before the transmission.
During the PPP negotiation, the peer of the PPP connection will indicate its MRU and will accept any value
up to that size. The actual MTU of the PPP connection will be set to the smaller of the two (MTU and the
peer’s MRU).
Ping:
Packet Internet Groper: A utility used to determine whether a particular device is online or connected
to a network by sending test packets and waiting for a response.
PPP:
Point-to-Point Protocol: A method of transporting and encapsulating IP packets between the user PC
and the ISP. PPP is full duplex protocol that is transmitted through a serial interface.
