Computers & Programming Notes

--------------------------------- --------------------------------- --------------------------------- ------------ Ping (Packet Internet Groper) The ping command is a  Command Prompt command  used to test the ability of the source computer to reach a specified destination computer. It's a simple way to verify that a computer can communicate with another computer or network device. It does this by transmitting Internet Control Message Protocol (ICMP) Echo Request messages and waits for a return message. Unless modified, the ping command will send  4 requests by default in Windows .  The two major pieces of information that the ping command provides are how many of those transmitted responses are returned and time it takes for each them to return. --------------------------------- --------------------------------- --------------------------------- ------------ NetStat (Network Statistics) The netstat is a command line tool used to display the current connections a...

  --------------------------------- --------------------------------- --------------------------------- ------------ Useful  : 1]  Click PDU  (Protocol Data Unit) In telecommunications, a protocol data unit (PDU) is a single unit of information transmitted among peer entities of a computer network. A PDU is composed of protocol-specific control information and user data.  In OSI model  each layer uses a different PDU  to communicate and exchange information, which can only be read by the peer layer on the receiving device and is then handed over to next upper layer after stripping. NOTE  :  The PDU defines the  state of the data  as it moves from one layer to the next. The protocol data unit changes between the seven different layers. The resulting information that is transferred from the application layer to the physical layer (and vice versa) is not altered, but the data undergoes a transformatio...