interview question for network administrator 9

What is D T E-Data Terminal Equipment. - It is a Digital device than generates, transmits and recieves messages. - Terminal here is used to show the movement of messages in and out of the terminal. - Server and the hosts maintain data and give information to Terminals. - Examples: TTY: Teletypewriter or Keyboard. ATMs. Automatic Teller Machines

Explain front end processcor (FEP). - It is a type of data Terminal Equipment which is a digital device used to input data and give the required output. - Performs data communications at host location. - Host can communicate with all data circuits present at its server. - The host location can also be remote from the server. - The main advantage of FEP is it avoids slow processing.

Explain line control Unit (LCU). - Performs communication related to remote location. - Directs the flow of data from communication channel to terminals present at remote location. - Perform serial to parrellel data conversion at transmitter and vice-versa at reciever. - Also perform the error detection and correction of the packets sent. - Control characters can be inserted or deleted from the packets easily .

Explain UART. - Called Universal asynchronous receiver transmitter. - Serial to parrallel conversion of data takes place at transmitter and vice –versa occurs at reciever. - Start and stop bits are send with data without any clock pulses for synchronization . - Formating of Data in Transmitter and Receiver takes place. - Also allows Voltage level conversion at both ends. Error detection and correction and bits synchronization is possible and data is sent in form of bytes.

Explain USRT. - Called universal synchronous receiver transmitter . - Here clocking information in form of bits is also transferred with the data. - Here no start and stop bits are transmitted with the data. - Parity bits are inserted and data sent in form of Blocks. - Transmit and receive status information is send or received. - The synchronous & asynchronous receiver transmitter can be combined forming USART.

Explain SNRM - Set normal response mode is an unnumbered command of synchronous data link control. - This command places secondary station into normal response mode. - In normal mode only the secondary station sends and receives information frames. - Secondary station remains in normal mode until it receives a disconnect command. - It is disconnected with an unnumbered acknowledgement.

What does address FF hex specify in SDLC address field. - Synchronous data link control address field is 8 bit and FF hex represents the last address. - This address is called as the broadcast address and is common to all secondary stations. - Frame sent with broadcast address is simultaneously sent to all other stations. - Since it is a 8 bit address so 256 addresses are possible. - Remaining address can also be used as unique stations or as groups.

Explain BSC - It is called as binary synchronous communications and is a type of synchronous data link protocol. - It is sometimes also called as the bisync or bisynchronous communications. - Each data transmission precedes a unique synchronization character (SYC). - The message block can be poll, selection or an acknowledgement. - The SYC character for ASCII is 16 hex.

What is block mode? - Block mode is a data transmission mode used for transmitting and receiving data. - Here data characters are not transmitted as they are typed. - Here initially the data characters are stored in buffers at the time of typing. - When the sender presses Enter key then only data is transmitted. - This set of characters stored in buffers and then sent are called blocks. - This mode is used in multidrop data communications.

Explain BOP. - BOP is called as the bit oriented protocol used in data link protocols. - It is used for serial bit by bit data transfer over communication channel. - These bits can be interpreted individually or groups of bits rather fixed length groups. - Here no dedicated data link control characters are required. - Example: high level data link communications (HDLC).