Data Base Management System NPTEL Week 5 Solutions

Q1. Identify the incorrect statement(s) about the 3-tier application architecture from the following.

a) The Controller Layer acts as the middle layer between the front and the database.
b) The Presentation Layer acts as the user interface between users and the database.
c) The Business Logic Layer acts as the middle layer between the front-end and the database.
d) The Data Access Layer acts as the backend of the application.

Answer: b)

Q2. Caching is used to improve web server performance. Which of the following sentences is not true about caching?

a) Caching is used on the server side for JDBC connection pooling.
b) Caching is used to increase the amount of data that needs to be sent over the network.
c) Web proxy caching is used to strore copies of frequently accessed Web objects.
d) Caching is used on the server side for generated HTML.

Answer: b)

Q3. A Redundant Arrays of Independent Disk (RAID) system has 8 disks and it uses block level striping to improve reliability. If we have to store a 16 KB file in it and the size of a disk block is 512 bytes. In which disk, the last file block will be stored?

a) Disk 8
b) Disk 7
c) Disk 1
d) Disk 0

Answer: a)

Q4. Which of the two alternatives would you choose if you need to support real-time queries that must be answered within a guaranteed short period of time?

a) Magnetic Hard Disk
b) Solid State Drive
c) Redundant Arrays of Independent Disks
d) Digital Video Disk

Answer: b), c)

Q5. If a system contains 1,000 disk drives, and each of them has a 6,00,000 hour MTBF (Mean time between failure), how often a single drive failure will occur in that disk system?

a) 25000 hours
b) 14400 hours
c) 600 hours
d) 25 hours

Answer: c)

Q6. Suppose you have a 64-gigabyte disk pack with the following specifications: 32 double-sided platters, 1024 tracks per surface, and 512 sectors per track. What is the data size of one sector?

a) 64 Kilobyte
b) 32 Kilobyte
c) 4 Kilobyte
d) 2 Kilobyte

Answer: d)

Q7. Consider the following string of reference:
33, 25, 81, 42, 33, 25, 50, 33, 25, 81, 42, 50
Find the number of replacements (where an existing value is replaced by a new value because the buffer is full) incurred using the least recently used (LRU) buffer replacement algorithm with 3 empty buffer frames.

a) 7
b) 8
c) 10
d) 12

Answer: a)

Q8. Consider the following schema:
Movie(movie_id, title, language, genre, director, year, production_company, reg_company)
production_company -> movie_id, title, language, genre, director, year
reg_company -> production_company
If you perform the schema refinement technique of Movie, which of the following statements will be true?

a) Table Movie do not need any refinement.
b) It is better to decompose in –
Movie(movie_id, title, language, genre, director, year)
Prodcution(production_company, reg_company)
c) It is better to decompose in –
Movie(movie_id, title, language, genre)
Direction(production_company, director, year)
Prodcution(production_company, reg_company)
d) It is better to decompose in –
Movie(movie_id, title, language, genre, director, year production_company)
Prodcution(production_company, reg_company)

Answer: d)

Q9. Consider the file organization for the relation Customer.
Which type of file organization is used to store the relation Customer?

a) Heap File Organization
b) Sequential File Organization
c) Hash File Organization
d) Multitable Clustering File Organization

Answer: a)

Q10. Which of the following statement(s) is(are) correct?

a) The disk controller acts as an interface between the computer system and the disk drive hardware.
b) When a sector is found to be bad, the disk controller remaps the logical sector to a different physical sector.
c) Mean time to failure (MTF) is the maximum time, for which a disk can run continuously without any failure.
d) When a huge number of disks are connected by a high-speed network to a number of servers, it is called Network Area Storage.

Answer: a), b)

Previous – Data Base Management System NPTEL Week 5 Solutions

Q1. Identify the incorrect statement(s) from the following options.

a) URL stands for unique resource locator
b) Common Gateway Interface is used to enable web servers to execute an external program
c) A cookie is a small piece of data containing identifying information
d) A web browser is a website that provides links to other websites

Answer: a), d)

Q2. Identify the universal frontend which connects database applications to the backend through internet.

a) SQL servers
b) Software applications
c) Web Servers
d) Web browsers

Answer: d)

Q3.

Answer: b)

Q4. Identify the incorrect statement(s).

a) Free list is a link list created from the deleted records of a file.
b) File pointers are some bytes that are allocated at the beginning of the file
c) A slotted page header is used in the file organization with fixed-length records
d) The records in a sequential file are ordered by the search-key

Answer: b), c)

Q5. Identify the correct statement(s) from the following.

a) RAID 0 is used only when data safety is important
b) RAID 1 is used in applications with a large amount of data and a low update rate
c) RAID 1 has a higher storage cost than RAID 5
d) RAID 5 is preferred in high update environments

Answer: c)

Q6. Consider a table Student(RollNo, Sname, Email, Dept).
The characteristics of its attributes are as follows:

Attribute RollNo has unique values
Attribute Sname has a wide range of string values
Attribute Email has many NULLs and the non-NULL values are not searched much
Attribute Dept has a narrow range of values

Which of these attribute(s) is(are) not good for indexing?

a) RollNo
b) Sname
c) Email
d) Dept

Answer: c)

Q7. Suppose a university maintains its students’ records in a database table. Each record is 200 byte long. The size of one disk block is 2 KB. Disk blocks can store only whole records. The data transfer rate of the disk is 64 KB per second. Whereas seek time is 24 milliseconds. The disk unit rotates at 4800 rpm (revolutions per minute). How much time will be required if a student wants to know his/her marks?

a) Approx. 33.38 millisecond
b) Approx. 61.5 millisecond
c) Approx. 67.75 millisecond
d) Approx. 600 millisecond

Answer: b)

Q8. Consider a hard disk drive with 256 tracks, numbered 0 to 255. The read-write head of the disk traverses the tracks in Shortest Seek Time First order. Which request will be served next after reaching track 92? If the pending requests in the queue are:
45, 85, 137, 92, 150, 165, 102, 172, 141
Suppose the read-write head was initially on track 35.

a) 150
b) 137
c) 85
d) 102

Answer: d)

Q9. Which of the following statement(s) is (are) correct?

a) The disk controller acts as an interface between the computer system and the disk drive hardware
b) Mean time to failure (MTTF) is the minimum time, when a disk can run continuously without any failure
c) When a sector is found to be bad, the disk controller remaps the logical sector to a different physical sector
d) When a huge number of disks are connected by a high-speed network to a number of servers, it is called Network Area Storage

Answer: a), c)

Q10.

Answer: a)

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Data Base Management System | NPTEL 2023 | Week 5 Assignment Solutions

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