UGC NET June-2018

#### Show Answer With Best Explanation

Explanation:
Given,
Frame size = 200 bits
Channel Bandwidth= 200 Kbps
System Produces = 250 frame per second

Throughput of the system = ?

Formula,
The Throughput of slotted ALOHA is S = G * e-G
The maximum Throughput Smax = 0.368 (or 36.8%) when G =1
Where, G is the average number of frames produced by the system during one frame transmission time.
The Frame Transmission time =

Calculation,
The Frame Transmission time = = 10-3 second = 1 millisecond
System Produces = 250 frame per second = (250 * 103 / 103) frame per second = (1/4) frame per millisecond
so, The Load (G) = 1/4 frame

S = G * e-G
= (1/4) * e-(1/4)
= 0.195 (or 19.5%) {where, e = 2.71}

Throughput = 250 * 0.195 = 49 Frames
Only 49 out of 259 frames will survive.

So, Option(I) is correct.

#### Show Answer With Best Explanation

Explanation:
Given,
Period(T) = 100ms

Formula used,

Calculation:

= second
= second
= 10 Hz
= Hz
= 10-2 KHz

So, Option(II) is correct.

#### Show Answer With Best Explanation

Explanation:
Dotted Decimal Representation: An IP address is a 32-bit number written in dotted decimal notation, four 8-bit fields (octets) converted from binary to decimal numbers, separated by dots.

10000001 00001011 00001011 11101111

convert 8-bit binary to decimal & seperate them by dots

129.11.11.239

So, Option(III) is correct.

#### Show Answer With Best Explanation

Explanation:
Switching: In large networks, there can be multiple paths from sender to receiver. The switching technique will decide the best route for data transmission.
Three broad categories of Networks are
(i) Circuit Switched Networks
(ii) Packet Switched Networks
(iii) Message Switched Networks

Circuit Switched Networks
• A dedicated path is establish between sender and receiver.
• Resources need to be reserved during the set up phase.

Packet Switched Networks
• Itis a switching technique in which the message is sent in one go, but it is divided into smaller pieces, and they are sent individually.
• There are two approaches to Packet Switching:
1) Datagram Packet switching:
• Resourse is reserved
• Connection oriented

2) Virtual Circuit Switching
• no Resourse is reserved
• Connectionless

Message Switching
• It is a switching technique in which a message is transferred as a complete unit and routed through intermediate nodes at which it is stored and forwarded.
• In Message Switching technique, there is no establishment of a dedicated path between the sender and receiver.
• Resources need not reserved during the set up phase.

Statement(a) : True
Statement(b) : False
Statement(c) : True

So, Option(III) is correct.

#### Show Answer With Best Explanation

Explanation:
Basic Concept
A substitution cipher replaces one symbol with another. Substitution ciphers can be categorized as
• Mono alphabetic
• Polyalphabetic ciphers

Shift Cipher
• The simplest monoalphabetic cipher is probably the shift cipher.
• The shift cipher is sometimes referred to as the Caesar cipher.
• The encryption algorithm is “shift key characters down,” with key equal to some number. The decryption algorithm is “shift key characters up.”

Calculation
W = 23 -15 = 8 (h)
T = 20 -15 =5 (e)
A = 1 – 15 = -14 + 26 = 12 (l) {when get negative number then add 26 to wrap arround}
A = 1 – 15 = -14 + 26 = 12 (l)
D = 4 – 15 = -11 + 26 = 15 (o)

Decrypted message = hello

So, Option(II) is correct.

#### Show Answer With Best Explanation

Explanation:
Given,
PainText = HELLO MY DEARZ

In encryption, we move the character at position 2 to position 1, the character at Position 4 to position 2, and so on.

CipherText =?

Calculation

So, Option(III) is correct.