Three-tier architecture includes which of the following?
Answer: B
Correct answer: A client layer and two server layers
The three tiers are the client, which presents; an application server, which holds the business logic; and a database server, which stores and retrieves. Placing the logic in a tier of its own is what allows the client to stay thin and the same rules to serve every client.
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Centralized systems are more susceptible to security threats than client/server architectures
Answer: B
Correct answer: False
A centralised system has one place to defend, one set of controls and one point of access. A client/server system spreads the data and the processing over many machines and a network, each of which can be attacked, so it is the distributed arrangement that is more exposed - not less.
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Activities of a DBMS occur in the processing component logic.
Answer: B
Correct answer: False
DBMS activity belongs to the storage logic component, which handles retrieval and storage of the data itself. Processing logic is where the business rules, validation and calculation live, and it is deliberately kept distinct from the storage layer so that either can change independently.
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Client/server environments use a local area network (LAN) to support a network of personal computers, each with its own storage, that are also able to share common devices and software attached to the LAN.
Answer: A
Correct answer: True
This is the ordinary client/server arrangement: personal computers with their own processing and storage, joined by a local network, sharing servers, printers and applications across it. The network is what makes the shared resources reachable and what distinguishes the arrangement from a set of standalone machines.
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Client/server security includes which of the following?
Answer: D
Correct answer: All of the above.
Security in a client/server system is only as good as its weakest component, and the components are numerous: the physical machines, the network, the client workstations, the server, and the procedures controlling changes to any of them. Securing the database alone leaves every other route open.
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The first client/server architectures developed were file servers.
Answer: A
Correct answer: True
The file server came first, sharing files across a local network with the processing left on the client. Its weaknesses - heavy network traffic and weak concurrency control, since each client worked on its own copy of the file - are what drove the move to database servers and to true client/server architectures.
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The three different application logic components are which of the following?
Answer: C
Correct answer: Presentation, Processing, and Storage
Every application does three things: it presents information to the user and accepts input, it applies the business rules, and it stores and retrieves data. Which machine performs each is what distinguishes a fat client from a thin one, a two-tier system from a three-tier one, and a file server from a database server.
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Which of the following is true concerning the mainframe?
Answer: C
Correct answer: Mission-critical systems have tended to remain there.
Mainframes have kept the workloads where reliability, throughput and long-established code matter most, and the move to client/server was largely a matter of new applications rather than migrated ones. The other options confuse the architectures - the mainframe is not client/server, and it is client/server that requires the split of code between workstation and server to be decided.
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An application program interface (API) is which of the following?
Answer: C
Correct answer: Middleware that provides access to a database.
An application program interface is the layer through which an application reaches a service, and in this context that service is the database. ODBC and JDBC are particular examples of such an interface rather than synonyms for the general term, and middleware that provides no database access is doing something else.
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A fat client is a PC configured for handling user interfaces and some application processing, usually with no or limited local data storage.
Answer: B
Correct answer: False
A PC handling the user interface and some processing with little or no local data is a thin client. A fat client takes on the presentation, extensive application logic and many database functions besides, which is why it needs a more capable machine and is harder to keep consistent across an organisation.
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