Client-Server and Peer-to-Peer Architectures

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Questions and Answers

What is the main function of a server in a network?

To send data only to other clients

To provide services to client devices (correct)

To connect network devices without processing data

To request data from client devices

Which statement accurately describes the difference between a switch and a router?

Both a switch and a router perform identical tasks in a network.

A switch directs packets, while a router connects devices.

A switch connects network devices, while a router directs packets to destinations. (correct)

A switch routes packets based on IP addresses, and a router connects multiple networks.

In which type of communication can both devices send and receive data simultaneously?

Simplex

Full-duplex (correct)

Half-duplex

Unidirectional

What is a significant disadvantage of using mesh topology?

Difficult installation and reconfiguration Signup and view all the answers

Which of the following is NOT an advantage of star topology?

Requires minimal cabling compared to tree topology Signup and view all the answers

What is a characteristic of bus topology?

Uses a long cable as a backbone and nodes connect through drop lines. Signup and view all the answers

What is one major disadvantage of bus topology?

Difficult reconfiguration and fault isolation Signup and view all the answers

In a full-duplex communication, which of the following is true?

Both devices can send and receive data simultaneously. Signup and view all the answers

What is one of the primary goals of web caching?

Satisfy client requests without involving the origin server Signup and view all the answers

How does HTTP/2 aim to mitigate head-of-line (HOL) blocking?

By dividing objects into frames and allowing client priority specification Signup and view all the answers

What is the purpose of the 'If-modified-since' header in a conditional GET request?

To prevent transmission of an object if the cached version is up-to-date Signup and view all the answers

What is a key benefit of modularization in complex systems?

Eases maintenance and updating of the system Signup and view all the answers

Which of the following is NOT a function of cookies?

Storing database records Signup and view all the answers

In a Client-Server paradigm, which characteristic is true for the server?

Is always on and has a permanent IP address Signup and view all the answers

Which component of an email system performs the role of sending and receiving messages?

Mail servers Signup and view all the answers

What is a primary feature of peer-to-peer architecture?

New peers increase service capacity and demands Signup and view all the answers

What method do processes on the same host use for communication?

Inter-process communication defined by the operating system Signup and view all the answers

What do open application-layer protocols enable?

Interoperability as they are publicly accessible Signup and view all the answers

Which transport service is primarily concerned with reliable data transfer?

Data integrity Signup and view all the answers

What type of application may tolerate some data loss during transmission?

Audio streaming applications Signup and view all the answers

What is a characteristic of proprietary protocols?

They can limit interoperability between systems Signup and view all the answers

What defines the transmission delay in packet delay components?

The packet length divided by link transmission rate Signup and view all the answers

What does 'dprop' represent in the context of packet delay?

Propagation delay along the physical link Signup and view all the answers

Which of the following describes the purpose of spyware malware?

To record keystrokes and upload information to a collector site Signup and view all the answers

What defines the denial of service (DoS) attack?

An attack that makes resources unavailable by flooding them with traffic Signup and view all the answers

What kind of throughput is measured as the rate over a specified longer period of time?

Average throughput Signup and view all the answers

Which of the following is an example of an application layer protocol?

IMAP Signup and view all the answers

How can malware spread in the case of a worm?

By passively receiving its payload and self-replicating Signup and view all the answers

In packet sniffing, what does the attacker do?

Interception and reading of data packets travelling across the network Signup and view all the answers

What is the main advantage of Frequency Division Multiplexing (FDM)?

Each call can transmit at the maximum rate of its assigned narrow band. Signup and view all the answers

What differentiates Time Division Multiplexing (TDM) from Frequency Division Multiplexing (FDM)?

TDM gives each call a periodic time slot, while FDM allocates narrow frequency bands. Signup and view all the answers

What role do Tier-1 ISPs play in the Internet structure?

They connect regional ISPs and do not pay anyone for their connectivity. Signup and view all the answers

What is an Internet Exchange Point (IXP)?

A meeting point where multiple ISPs can connect and peer. Signup and view all the answers

How does Google manage its data centers globally?

By interconnecting data centers via its private TCP/IP network. Signup and view all the answers

What is one of the main financial models for IXPs?

IXPs charge ISPs based on the traffic exchanged. Signup and view all the answers

Which of the following describes a benefit of peering at IXPs?

It allows ISPs to exchange traffic without incurring transit fees. Signup and view all the answers

What can be inferred about Google's strategy with lower-tier ISPs?

Google seeks to establish direct connections with lower-tier ISPs. Signup and view all the answers

What happens in a ring topology if there is a disabled station?

The entire network may become disabled. Signup and view all the answers

Which of the following describes a PAN?

It provides data transmission among personal devices. Signup and view all the answers

Which statement about tree topology is accurate?

It has a central node that acts as a trunk. Signup and view all the answers

What is one disadvantage of ring topology?

A break in the ring can disable the whole network. Signup and view all the answers

What defines network protocols?

They define the format and order of messages among network entities. Signup and view all the answers

Which components are typically part of the network edge?

Clients and servers Signup and view all the answers

How does a local area network (LAN) primarily function?

It operates within a limited area. Signup and view all the answers

What is the primary role of the central node in a tree topology?

To act as a central point for device connections. Signup and view all the answers

Study Notes

Client-Server Paradigm

A server is always on and has a permanent IP address, often in data centers
Servers are used for scaling issues
Clients contact servers, and communicate with servers, but not directly with each other
Clients may have dynamic IP addresses
Examples of Client-Server paradigms include HTTP, IMAP, and FTP

Peer-to-Peer Architecture

End systems communicate directly
Peers request service from other peers and provide service in return
Peer-to-peer systems offer self-scalability; new peers add new service capacity
Peers may connect and disconnect intermittently, and change IP addresses
Examples include P2P file sharing

Process Communication

A process is a program running within a host
Processes on the same host communicate using inter-process communication (defined by the OS)
Processes on different hosts communicate by exchanging messages

Sockets

A process sends and receives messages through sockets

Application-Layer Protocols

Defines message types, syntax, semantics, and rules for message exchange
Examples include HTTP, SMTP, and FTP
Open protocols, like HTTP, are defined in RFCs (Request For Comments)
Proprietary protocols like Skype are not standardized

Transport Services

Data integrity: Some apps need reliable data transfer (e.g., file transfer)
Timing: Some apps need low delay (e.g., interactive games)
Throughput: Some apps need a minimum amount of throughput (e.g., multimedia)

Internet Transport Protocols

TCP (Transmission Control Protocol): reliable transport, flow control, congestion control, but not timing or security
UDP (User Datagram Protocol): unreliable transport (no guarantees); no flow or congestion control

HTTP Connections

Non-persistent HTTP: Each object requires a separate TCP connection
Persistent HTTP: Multiple objects can be sent over a single TCP connection

HTTP Response Time

Non-persistent HTTP response time is approximately 2 Round Trip Time (RTT) + file transmission time

HTTP Request Types

POST: Web page often includes form input – user input is sent in the entity body
GET: User data is in the URL field following a '?'
HEAD: Returns only request headers (without the object body)

HTTP Response Status Codes

200 OK: Request succeeded
301 Moved Permanently: Requested object has moved to a new location
400 Bad Request: Request message is not understood
404 Not Found: Requested object not found on the server
505 HTTP Version Not Supported: The requested HTTP version is not supported by the server

Cookies

Used by websites and clients to maintain some state between transactions, such as cookies for shopping carts

Web Caching

Goal: Satisfy client requests without involving the origin server
Web caches act as both client/server, reducing response time and overall request loads

Conditional GET

Don't send object if the cache has an up-to-date version

HTTP 1.1 with Multiple Object Pipelining

Introduced pipelined GETs using TCP connection for faster transmission

HTTP/2 Goal and HOL Blocking Mitigation

Goal: Decreased delay in multi-object HTTP requests by allowing servers to send objects to the client
Addressing methods, status codes, and header fields – and dividing objects into frames

Email Components

User Agents
Mail Servers
SMTP (Simple Mail Transfer Protocol)

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Description

Explore the fundamental concepts of Client-Server and Peer-to-Peer architectures with this quiz. Understand how processes communicate within hosts and the role of sockets in message exchange. Test your knowledge on key examples and characteristics that differentiate these networking paradigms.