CBSE Guess > Papers > Important Questions > Class XII > 2011 > Computer Science > Computer Science By Mr. Kapil Bhatia

CBSE CLASS XII

Basic Theory (Part 2)

Page 6 of 7

21. What is the purpose of using FTP?

Ans. FTP is a network protocol which is used to transfer file(s) from a computer at one location to remote computer , usually over the internet. FTP stands for File Transfer Protocol.

22. Give two advantages and disadvantages of BUS, Ring and Tree topology.

Ans. BUS topology advantages:

1. Length of the cable is small.
2. Layout of the cable is very simple.

Disadvantages:

1. Fault in the backbone cable can upset the function of the whole network.
2. Fault diagnosis is difficult.

Ring Topology:

1. it is characterized by data flow around the ring on one or two direction. Sharing the ring through token, each node being connected to its neighboring node.
2. Short cable length and less connection will be needed which increase network reliability.

Disadvantage:

1. Since each node in this network connected to its neighbouring node and data is travel through each node. There is one traffic flow until defective node is removed. This causes network failure.
2. in this topology this is difficult to diagnoses fault and re- configure network is also difficult.

Tree Topology:

1. Suitable for hierarchical flow of data.
2. This make it easier to isolate a defective bode.

Disadvantages:

1. Low speed. The data transmission is slow.
2. Fault isolation is difficult.

23. What is the difference between MAN and WAN?

Ans.                                MAN                                                     WAN

1. Diameter limited to the area of the city.               Span entire country.
2. A data rate of several Mbps.                                  Data rate less than 1 Mbps.

24. Write the two advantages of using include compiler directive.

Ans. The preprocessor directive # include tells the compiler to insert another file into the source file. The two advantages are;

1. The program is broken down into modules thus making it more simplified.
2. More library functions can be used at the same time size of the program is retained.

25. Illustrate the use of this pointer.

Ans. The member function of every object has access to a sort of magic pointer named this, which points to the object itself. The this pointer useful in returning the object (address) of which the function is a member.

26. Distinguish between serial and sequential file.

Ans. In the serial file there is no importance of primary key field. Record are stored in the order they arrived and also retrieved in the same order. Record cannot be arranged according to a key value in a serial file.

In the sequential file, records can be written in a specific order of key field. Record retrieval is in the same order of key field.

27. What are DDL and DML?

Ans. DDL: Statement is the another category of SQL statements, these statements define, delete, modify database objects. E.g., CREATE TABLE, DROP TABLE, ALTER TABLE.

DML: Statement is the another category of SQL statements, After the database objects have been created, data can be manipulated using the special set of statements called data manipulation language. E.g. INSERT, UPDATE, DELETE.

28. Name two switching circuits and explain.

Ans. Two switching mechanisms are in use for digital data transmission. They are circuit switching and Packet switching.

Circuit switching: Is the process in which complete route is established well in advance before data is transmitted. Every intermediate computer is act as a switched device which receives data as an input and diverts it as output through the appropriate channel. The process is repeated until the correct destination is reached.

Packet Switching: In this switching technique no path is establish in advance. The data to be transmitted is store in source computer and forwarded later one heap at a time. The number of bytes transmitted in one lot is known a packet. The size of each packet is fixed. The packet is buffered in the RAM of the intermediate computer. The packet contains the address of the destination to which the packet will be directed.

29. Distinguishing between ios::out and ios::app.

Ans. ios::out is used to create a new data file. If said name already exists, this statement overwrite them. ios::app is used to append data at the end of existing data file.

30. What is the purpose of header file in a program?

Ans: The c++ language contains some statement only and not any built-in function. Reather it provides standard library that contains files storing the standard functions these files are know as header files. Header files provide function prototype , definition of library function.

 

Submitted By Mr. Kapil Bhatia
Email Id : [email protected]