3i Infotech Papers: Sample Questions 144 - 145 of 1245

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Question number: 144

» Basic CS » Networks

Essay Question▾

Describe in Detail

Difference between switching and routing.

Explanation

Difference between switching and routing.

Difference between switching and routing.

Router

Switch

Provides direct data in a network.

Allow connecting multiple device and its ports can be managed.

Network Layer (Layer 3) devices

Data Link Layer device.

Data transmission is in form packet

Data transmission is in form frame (L2 switch) or frame & packet (L3 switch)

Used in LAN, WAN

Used in LAN

Device type- networking device

Device type- active & networking device

Transmission Mode- Full duplex

Transmission Mode- half or full duplex

Address used for data- IP address

Address used for data- MAC address

Question number: 145

» Database » MySQL

Essay Question▾

Describe in Detail

How can you find the minimal key of relational schema?

Explanation

  • Minimal key can identify each tuple of the relation schema uniquely.

  • For finding the minimal key- find the closure that is the set of all attributes dependent on any given set of attributes under the given set of functional dependency.

Algo I:

I Determining , closure for X, given set of FDs F

1. Set

2. Set Old

3. For each FD Y Z in F and if Y belongs to then add Z to

4. Repeat steps 2 and 3 until Old

Algo. II

Determining minimal K for relation schema R, given set of FDs F

1. Set K to R that is make K a set of all attributes in R

2. For each attribute A in K

a. Compute with respect to

b. If then set