DISTRIBUTED SYSTEMS (ch.1) ( EXAM
QUESTIONS WITH 100%VERIFIED
ANSWERS
A distributed system is a collection of autonomous computing elements that appears to its users
as a single coherent system. - ✔✔T
A distributed system is a collection of computing elements (hardware devices or software
processes) each being not being able to behave independently of each other. - ✔✔F (being
able to behave independently of each other)
Users of a distributed system (be they people or applications) believe they are dealing with
multiple systems. - ✔✔F (single coherent system)
We can assume that there is something like a global clock across a distributed system. - ✔✔F
(Each node will have its own notion of time)
Since each node is independent, we need group management and authentication. - ✔✔T
In closed groups, any node can join the distributed system, effectively meaning that it can send
messages to any other node in the system. - ✔✔F (open groups)
In closed groups, only the members of a group can communicate with each other. - ✔✔T
In open groups a separate mechanism is needed to let a node join or leave that group. - ✔✔F
(closed groups)
A distributed system is often organized as an overlay network. - ✔✔T
,In overlay networks, a node is typically a software process equipped with a list of other
processes it can directly send messages to. - ✔✔T
An overlay network can be not connected sometimes. - ✔✔F (should always be connected)
In an unstructured overlay, each node has a well-defined set of neighbors with whom it can
communicate. - ✔✔F (structured overlay)
Tree and logical rings are examples of structured overlay networks. - ✔✔T
In an unstructured overlay network, each node has several references to randomly selected other
nodes. - ✔✔T
Achieving a single-system view is a must in distributed systems. - ✔✔F (a distributed systems
appears to be coherent)
A distributed system is coherent if it behaves according to the expectations of its users. - ✔✔T
In a distributed system the collection of nodes operates differently, depending on where, when,
and how interaction between a user and the system takes place. - ✔✔F (a single coherent
system ==> thus operates the same...)
Hiding partial failures and their recovery is often very difficult and in general impossible. -
✔✔T
Middleware is the same to a distributed system as what an operating system is to a computer. -
✔✔T
The middleware layer resides below the application layer and above the operating system
offering the same interface to applications no matter what machine or what operating system the
application is running on. - ✔✔T
, o Facilities for inter-application communication.
o Security services.
o Accounting services.
o Masking of and recovery from failures.
The above are services that are offered offered by the middleware that can be found in most
operating systems - ✔✔T
There are no differences between middleware and operating systems. - ✔✔F (main difference
is that middleware services are offered in are offered in a networked environment)
Typical middleware services also include:
o Communication
o Transactions:
o Service composition
o Reliability. - ✔✔T
Remote Procedure Calls (RPCs) is an example of communication services offered by the
middleware. - ✔✔T
It is acceptable that a transaction can be only executed partly since distributed systems only
APPEAR to be a single coherent systems and executing transactions is a service offered by
distributed systems. - ✔✔F (transactions must be executed in an all-or-nothing fashion)
Google maps viewing the weather on different locations is an example of an application making
use of services offered by a distributed system. - ✔✔T (making use of service composition
service)
QUESTIONS WITH 100%VERIFIED
ANSWERS
A distributed system is a collection of autonomous computing elements that appears to its users
as a single coherent system. - ✔✔T
A distributed system is a collection of computing elements (hardware devices or software
processes) each being not being able to behave independently of each other. - ✔✔F (being
able to behave independently of each other)
Users of a distributed system (be they people or applications) believe they are dealing with
multiple systems. - ✔✔F (single coherent system)
We can assume that there is something like a global clock across a distributed system. - ✔✔F
(Each node will have its own notion of time)
Since each node is independent, we need group management and authentication. - ✔✔T
In closed groups, any node can join the distributed system, effectively meaning that it can send
messages to any other node in the system. - ✔✔F (open groups)
In closed groups, only the members of a group can communicate with each other. - ✔✔T
In open groups a separate mechanism is needed to let a node join or leave that group. - ✔✔F
(closed groups)
A distributed system is often organized as an overlay network. - ✔✔T
,In overlay networks, a node is typically a software process equipped with a list of other
processes it can directly send messages to. - ✔✔T
An overlay network can be not connected sometimes. - ✔✔F (should always be connected)
In an unstructured overlay, each node has a well-defined set of neighbors with whom it can
communicate. - ✔✔F (structured overlay)
Tree and logical rings are examples of structured overlay networks. - ✔✔T
In an unstructured overlay network, each node has several references to randomly selected other
nodes. - ✔✔T
Achieving a single-system view is a must in distributed systems. - ✔✔F (a distributed systems
appears to be coherent)
A distributed system is coherent if it behaves according to the expectations of its users. - ✔✔T
In a distributed system the collection of nodes operates differently, depending on where, when,
and how interaction between a user and the system takes place. - ✔✔F (a single coherent
system ==> thus operates the same...)
Hiding partial failures and their recovery is often very difficult and in general impossible. -
✔✔T
Middleware is the same to a distributed system as what an operating system is to a computer. -
✔✔T
The middleware layer resides below the application layer and above the operating system
offering the same interface to applications no matter what machine or what operating system the
application is running on. - ✔✔T
, o Facilities for inter-application communication.
o Security services.
o Accounting services.
o Masking of and recovery from failures.
The above are services that are offered offered by the middleware that can be found in most
operating systems - ✔✔T
There are no differences between middleware and operating systems. - ✔✔F (main difference
is that middleware services are offered in are offered in a networked environment)
Typical middleware services also include:
o Communication
o Transactions:
o Service composition
o Reliability. - ✔✔T
Remote Procedure Calls (RPCs) is an example of communication services offered by the
middleware. - ✔✔T
It is acceptable that a transaction can be only executed partly since distributed systems only
APPEAR to be a single coherent systems and executing transactions is a service offered by
distributed systems. - ✔✔F (transactions must be executed in an all-or-nothing fashion)
Google maps viewing the weather on different locations is an example of an application making
use of services offered by a distributed system. - ✔✔T (making use of service composition
service)
