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A transaction is made to wait until all ________ locks held on the ite...

  • Q. A transaction is made to wait until all ________ locks held on the item are released
  • filter_dramaExplanation
    Answer is : A
    A transaction is made to wait until all compatible locks held on the item are released. This ensures that no other transaction is concurrently accessing the same item.

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  • 1.

    Consider the following statements:

    S1: In distance vector routing, each router maintains a routing table indexed by, and containing one entry for each router in the network.

    S2: Link state routing requires more memory and computation as compared to distance vector routing.

    Which of the given statements is/are true?

  • filter_dramaExplanation
    Answer is : C

    Answer: Option 3

    Explanation

    Both S1 and S2 are true.

    In distance vector routing, each router maintains a routing table indexed by and containing one entry for each router in the network. This entry has two parts: the preferred outgoing line to use for that destination and an estimate of the distance to that destination. The distance might be measured as the number of hops.

    Compared to distance vector routing, link state routing requires more memory and computation. For a network with n routers, each of which has k neighbours, the memory required to store the input data is proportional to kn, which is at least as large as a routing table listing all the destinations.

  • 2.

    Which of the statement are true?

    Statement 1: All NoSQL databases support ACID transactions.

    Statement 2: NoSQL databases come in a variety of types based on their data model.

  • filter_dramaExplanation
    Answer is : D

    The correct answer is option 4.

    Concept:

    Statement 1: All NoSQL databases support ACID transactions.

    False, NoSQL databases do not need a fixed table structure and do not provide full ACID support.  There's nothing about NoSQL data models that imply ACID transactions aren't possible. Some NoSQL distributed systems don't have them

    Statement 2: NoSQL databases come in a variety of types based on their data model.

    True, NoSQL databases ("not only SQL") are non-tabular databases and store data differently than relational tables. NoSQL databases come in a variety of types based on their data model. The main types are document, key-value, wide-column, and graph.

    Hence the correct answer is Only statement 2 is true.

  • 3.

    Consider the following relation.

    Cinema (theater, address, capacity)

    Which of the following options will be needed at the end of the SQL query

    SELECT P1.address

    FROM Cinema P1

    such that it always finds the addresses of theaters with maximum capacity?

  • filter_dramaExplanation
    Answer is : A

    SELECT P1.address

    FROM Cinema P1

    WHERE P1. Capacity > = All (select P2. Capacity from Cinema P2)

    The above query will find the addresses of theatres with maximum capacity.

  • 4. Find the routing table. If node A is connected to B with weight 5, to node C with weight 2, and to node D with weight 3. Node C is connected to node A with weight 2, to node B with weight 4 and to node E with weight 4. Node B is connected to E with weight 3.
  • filter_dramaExplanation
    Answer is : B

    Answer Option 2

    Explanation

     node A is connected to B with weight 5, to node C with weight 2, and to node D with weight 3.

    Table at A:

    Node

    Weight

    Next Router

    A

    0

    -

    B

    5

    -

    C

    2

    -

    D

    3

    -

    E

    -

    -

     

     Node C is connected to node A with weight 2, to node B with weight 4, and to node E with weight 4.

    Table at C:

    Node

    Weight

    Next Router

    A

    2

    -

    B

    4

    -

    C

    0

    -

    D

    -

    -

    E

    4

    -

     

    Node B is connected to E with a weight of 3

    Table at B:

    Node

    Weight

    Next Router

    A

    -

    -

    B

    0

    -

    C

    -

    -

    D

    -

    -

    E

    3

    -

     

    In Routing table of A

    Cost A->E = Min( A->B + B->E , A->C + C->E ) ≡ Min(5+3 , 2+4) ≡ Min(8,6)

    Hence Cost A->E = 6

    final Routing table at A

    Node

    Weight

    Next Router

    A

    0

    -

    B

    5

    -

    C

    2

    -

    D

    3

    -

    E

    6

    C

     

    Hence Option 2 is the correct answer.

  • 5. Which of the following is a part of Layer 2 Ethernet Frame?
  • filter_dramaExplanation
    Answer is : D

    The preamble consists of a 56-bit (seven-byte) pattern of alternating 1 and 0 bits, allowing devices on the network to easily synchronize their receiver clocks, providing bit-level synchronization. It is followed by the SFD to provide byte-level synchronization and to mark a new incoming frame

    Layer 2 Ethernet Frame Format:

    MAC destination

    MAC

    Source

    VLAN tag

    (Optional)

    Frame Length

    Payload

    Frame Check Sequence (CRC)

    6 Byte

    6 Byte

    2 Byte

    2 Byte

    46-1500 Byte

    4 Byte

     

    Layer 1 Frame Format:

    Preamble

    Start of frame Delimiter

    MAC destination

    MAC

    Source

    VLAN tag

    (Optional)

    Frame Length

    Payload

    Frame Check Sequence (CRC)

    7 Byte

    1 Byte

    6 Byte

    6 Byte

    2 Byte

    2 Byte

    46-1500 Byte

    4 Byte

     

    Start of frame delimiter and Preamble are not present in Layer 2 Ethernet Frame 

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