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Perguntas do quiz (60)
1Which of the followings are true about vertical fragmentation of a table in
distributed storage design?- AOnly one of the fragments must include the primary key column(s) of the original table
- BAll fragments must include the primary key column(s) of the original table
- CThe fragments may not include the primary key column(s) of the original table
- DVertical fragmentation must allow table re-construction from the fragments
2For which type of logical clocks the event timestamp must include the processor
index for having a totally ordered events in a distributed system?- AScalar time
- BVector time
- CBoth scalar time and vector time
3Which of the followings are true about atomic commit protocols in distributed
transactions?- AEach Participant must call the join() operation defined by the Coordinator interface
- BThe Coordinator must call the join() operation defined by Participants' interface
- CIn a distributed transaction, the Coordinator must have the references to all Participants
4Check all true statements about Virtual Machines (VMs).
- AAll VMs running on the same server must have the same guest Operating System
- BVMs can be replicated in multiple servers
- CVM instances may be created from a template VM
- DThe virtualization layer provides services for data exchange between VMs
5Which of the followings are specific only to distributed deadlocks?
- ADeadlock situations are detected by using wait-for graphs
- BDeadlock situations are detected by using timeout timers
- CA phantom deadlock situation may happen during a deadlock detection process
6Concurrency control is the main task of:
- ARecovery Manager
- BData Manager
- CScheduler
- DTransaction Manager
7Which of the following is the correct definition of the reliable one to one
communication:- AAny message in the outgoing message buffer is delivered to the incoming message
buffer - BThe message received is identical to one sent, and no messages are delivered twice
- CAny message in the outgoing message buffer is delivered to the incoming message
buffer and the message received is identical to one sent, and no messages are delivered
twice
- AAny message in the outgoing message buffer is delivered to the incoming message
8The transparency type that offers the same interface to a service, no matter if it is
local or remote is called:- AAccess transparency
- BLocation transparency
- CMigration transparency
- DConcurrency transparency
9Check all true statements about a Global Conceptual Schema (GCS)
- AIncludes how distributed tables are fragmented
- BIncludes storage locations for distributed tables
- CIncludes information about tables replication
- DIncludes all primary keys of the tables
- EIncludes all foreign keys of the tables
10Google App Engine (GAE) is a type of:
- AInfrastructure as a Service
- BSoftware as a Service
- CPlatform as a Service
- DNone of the indicated answers
11(True or False) Failure is easier to be detected for synchronous distributed systems
than for asynchronous distributed systems- AVerdadeiro
- BFalso
12In which type of virtualization technique the guest operating system needs to be
modified to be adapted to the hypervisor?- AFull Virtualization of type 1
- BFull Virtualization of type 2
- CPara-Virtualization
- DHardware-assisted Virtualization
13(True or False) In a distributed system, strong consistency of replicated data has a
positive impact over latency.- AVerdadeiro
- BFalso
14Check all true statements about a RPC client stub
- AIt should be compiled and linked with the client code
- BIt should be compiled and linked with the server code
- CIt should implement the remote procedure
- DIt is used to achieve the goal of semantic transparency
15Check all true statements about a binding agent used in client - server binding
process- ABinding agent location should be known by both servers and clients
- BBinding agent location should be known only by the clients
- CCommunication overhead is low when most of the clients are short lived
- DReplicated binding agents involves high overhead
- EReplicated binding agents involves low overhead
16An interprocess communication where both send and receive operations are
blocking operations is called:- ATransient communication
- BPersistent communication
- CSynchronous communication
- DAsynchronous communication
17Which of the following statements are true about Chandy-Lamport snapshot
algorithm?- AIt works for all types of communication networks
- BIt works only for specific communication networks
- CThe marker must be sent by a node before taking its snapshot
- DThe marker must be sent by a node after taking its snapshot
- EA node may send the marker before or after taking its snapshot
18Which of the followings are true about table fragmentation in distributed storage
design:- Atable fragments must not be replicated
- Btable fragments must be stored at different sites
- Ctable fragmentation increases data processing parallelism
- Dtable fragmentation helps in case of disaster recovery
19Which of the followings are true about nested distributed transactions?
- AChildren sub-transactions may run on different machines
- BChildren sub-transactions must run on the same machine
- CChildren sub-transactions may run in parallel
- DFor consistency reasons, children sub-transactions must be executed one after the
other
20Consider a transaction T operating on an object x and transaction U operating on
an object y.
Check all true statements below- AT read / U read is a conflicting situation
- BT read / U write is a conflicting situation
- CT write/ U read is a conflicting situation
- DT write / U write is a conflicting situation
- EThe mentioned operations are not conflicting situations
21Check the true statement
- AAsynchronous distributed system failures can be detected by using timeout timers
- BSynchronous distributed system failures can be detected by using timeout timers
- CTimeout timers can be used for failure detection in both synchronous and asynchronous
distributed systems
22Which of the followings is true about a flat distributed transaction?
- AEach transaction operation must be completed before executing another operation
- BEach transaction operation must be executed at a different site
- CTransaction operations may be executed in parallel
23The unwanted situation that may happen, when the acquired locks are
progressively released before transaction execution completion is called:- ALost update situation
- BInconsistent retrieval situation
- CCascading abort situation
- DDeadlock situation
24Which of the followings is true about the events in a distributed system?
- AThe timestamp of an event represents the physical time when the event happened
- BConcurrent logical events must occur at the same physical time
- CLogically concurrent events are not causally related events
25Which ACID property describes the fact that all transaction effects should be saved
into permanent storage after the successful transaction commit.- AConsistency
- BIsolation
- CDurability
- DAtomicity
26Which of the followings are features of Optimistic Concurrency Control (OCC)
technique?- AIt is recommended for private workspace transaction implementations
- BIt is recommended for write-ahead log transaction implementations
- CThere are no conflicts in OCC, hence all concurrent transactions may commit without
any validation - DIn OCC all transactions must be validated before they are allowed to commit
27Which of the followings represent benefits of resource virtualization?
- AServer consolidation
- BElastic usage of hardware resource
- CAvoids single points of failure
- DLimited infrastructure and resource demand
28(True or False) Data replication improves data consistency
- AVerdadeiro
- BFalso
29The ability of a distributed system to limit the latency due to system faults is
called:- AReliability
- BConsistency
- CAvailability
- DEfficiency
30Which of the following statements are true about the atomic Two-Phase Commit
Protocol (2PC) for Distributed Transactions?- AThe participants must save the involved transaction data into permanent storage before
voting commit - BThe participants must save the involved transaction data into permanent storage after
voting commit - CEach protocol step defines a timeout timer for avoiding algorithm blocking
- DThe coordinator may decide to commit the transaction even if a participant voted abort
- AThe participants must save the involved transaction data into permanent storage before
31Which of the following statements represent false assumptions about a
Distributed System?- ALatency is zero
- BNetwork is reliable
- CUses the asynchronous communication model
- DTopology does not change
32Which of the following statements is true about time-space diagrams:
- AThey show the time evolution of a distributed system showing the processes, atomic
events execution and the messages exchanged by the processes - BTogether with the concept of “cut” they define the Lamport scalar time
- CThey show the time usage of the memory space in the distributed system
- DThey help identifying security problems in a distributed system
- AThey show the time evolution of a distributed system showing the processes, atomic
33Which of the following objectives should be achieved by concurrency control
algorithms?- AGuarantee that multiple transactions can be executed simultaneously while still
being isolated - BSchedule individual read/write operations as to achieve transaction isolation and
consistency - CIncrease data security and privacy across several transaction
- AGuarantee that multiple transactions can be executed simultaneously while still
34The global state of a distributed system (choose the right answer):
- AIs represented by the state of all processes and of all communication channels
- BIs represented by the state of all processes and their sent messages
- CIs represented by a snapshot of the memory of the distributed system’s processing
nodes - DIs represented by a snapshot of the messages in transit in the communication
channels
35Which of the following statements referring to Message Queues
communication between processes are correct?- AIt is a type of direct communication
- BIt is a type of indirect communication
- CThe communication entities must be active at the same time
- DThe communication entities may not be active at the same time
36In a transaction related pessimistic concurrency control algorithm (choose the
right answer):- ATransactions are executed without checking for serializability condition
- BTransactions operation are synchronized before they are executed
- CTransactions operation are synchronized after they are executed
- DTransactions are executed and the check for serializability is done right after
committing
37The Mean Time To Failure (MTTF) is a measure that is specific to (choose the
right answer):- AAvailability
- BPerformance
- CReliability
- DConsistency
38In a Distributed Database Environment, the Global Conceptual Schema contains
information about (choose the right answer):- AThe locations where the individual tables are stored
- BThe database tables, their columns, data types, primary and secondary keys, etc.
- CHow the database tables are fragmented and where the fragments are located
39Which of the following statements is true about Chandy-Lamport snapshot
algorithm for FIFO channels?- AThe marker is sent by a site before taking its snapshot
- BThe marker is sent by a site after taking its snapshot
40Which of the following statements are true for a P2P system?
- AA P2P system consists of many server processes and many client processes
- BA P2P system consists of one server process and many client processes
- CAll P2P processes offer the same interfaces
- DAll P2P processes run the same program
41Which of the following statements describe the vertical fragmentation of a
database?- ASplits a table and groups the columns into fragments
- BSplits a table and groups the rows based on the values of one or more columns
- CSplits a tables and groups the rows based on the rows of another table
- DSplits a tables and groups the rows based on the column of another table
42To improve low utilization ratio of server machines in virtual clusters it is
recommended to (choose the right answer):- AIncrease servers' memory
- BPerform server consolidation
- CAllocate the execution of the same task on more servers
- DAdd new server machines
43Which type of cloud service provides resources allow the users to develop,
deploy, and manage the execution of their applications?- AInfrastructure as a Service (IaaS)
- BPlatform as a Service (PaaS)
- CSoftware as a Service (SaaS)
44CAP theorem states that every distributed system can provide only two of the
following properties (choose the right answer):- AConsistency, Availability, Performance
- BConsistency, Availability, Partition-Resilience
- CConsistency, Access, Performance
- DConcurrency, Availability, Partition-Resilience
45Which of the following are true about logical clocks
- Athey capture the event causality in a more accurate way than physical time
- Bthey measure the time between two distributed system events
- Cthe time measured is expressed in nanoseconds
- Dthey can be used to timestamp the events of a distributed system execution
46In RPC mode a stub is:
- Aa remote procedure implemented by a server
- Ba proxy of a remote procedure
- Ca server side dispatcher module used to identify the procedure to be executed
47Which of the following statements are true in case of full virtualization:
- AGuest OS knows that it is running in virtualized environment
- BGuest OS is completely abstracted from the underlying infrastructure
- CGuest OS is used without any modification
- DGuest OS is modified to replace non-virtualizable instructions with hypercalls
48Bi-directional streaming is (choose the appropriate answer):
- Aa feature of all RPC technologies
- Ba feature of gRPC
- Ca feature of virtualization
49Which of the following is a feature of a Distributed System (DS)?
- AIf one node fails, the rest of the DS nodes will stop execution
- BIf one node fails, only the directly connected nodes to the failed node will stop
execution - CIf one node fails, the rest of the nodes will continue to operate
50Which of the following represent benefits of resource virtualization?
- AElastic usage of hardware resource
- BServer consolidation
- CLower energy consumption
51Which of the following statements are true for a Distributed Transaction (DT)?
- AA DT must be of all or nothing semantics
- BA DT generates a transition of a database from a consistent state to a consistent
state - CDT’s effect is transparent to other transactions until it commits
- DA deadlock situation may occur in all concurrent executed DTs no matter of the
concurrency control technique
52Which of the following is NOT true about Java RMI?
- AParameters can be passed both by reference and by value
- BThe distributed object interface must be deployed both on client and server
- CThe distributed garbage collector counts both local and remote references to an
object - DRMI Registry is a reference implementation for a naming service
53Which of the following must be satisfied by the global state of a distributed
system to be consistent?- AEvery message recorded as sent by the sender processor should be in the
communication channel or already received by the destination process - BIf a message is not recorded as sent it cannot be in the communication channel or
already received - CThere should be no messages in the communication channels
- DThe order of the sent messages recorded at the sender processes should be the
same at the receiving processes
- AEvery message recorded as sent by the sender processor should be in the
54A database is said to be distributed if (check all true statements):
- AAll its stored data is localized at a single site
- BAny of its tables are stored at different sites
- COne or more of its tables are replicated and their copies are stored at different sites
- DOne or more of its tables are fragmented and the fragments are stored at different
sites
55In a two-phase locking algorithm (check all true statements):
- AIn the Growing Phase, the scheduler acquires all the locks a transaction is needed
- BIn the Growing Phase, the scheduler acquires all the locks needed for write
operations - CIn the Shrinking Phase the scheduler releases the locks as each operation completes
- DIn the Shirking Phase the scheduler releases all locks at once after transaction
terminates
56Which type of failures are also known as Byzantine failures?
- AThe omission failures
- BThe arbitrary failures
- CThe timing failures
- DThe masking failures
57An explicit wait-for graph may be used for implementing (choose the right
answer):- AA deadlock detection technique for lock-based concurrency control
- BA deadlock detection technique for optimistic concurrency control
58In the One Phase Atomic Commit protocol (check all true statements):
- AThe coordinator takes the commit or abort decision
- BThe participants vote commit or abort
- CThe coordinator together with the participants take the commit or abort decision
using voting - DThe participants cannot decide to abort the transaction on their own
59System Throughput is:
- Aan indicator of availability
- Ban indicator of the number of queries/requests per second
- Can indicator of durability
60In transaction implementation technique based on write-ahead logs (check all
true statements):- AEach of the participant nodes keeps its own log of transaction changes
- BOnly the coordinator keeps a log of transaction changes
- CThe data is effectively changed only after the log is written successfully
- DThe data is changed and then, the modification is written to the log
Informações
- Descrição
- Computer Science Quiz sobre grile sd, criado por Iulia Tia Stoian em 18-01-2022.
- Autor
- Iulia Tia Stoian
- Idioma
- English
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