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Questions and Answers
What is the primary goal of a conditional GET request in HTTP?
What is the primary goal of a conditional GET request in HTTP?
What is the effective data rate to browsers over the access link if the cache hit rate is 0.4?
What is the effective data rate to browsers over the access link if the cache hit rate is 0.4?
Which FTP port is designated for control connections?
Which FTP port is designated for control connections?
Which of the following is NOT a component of electronic mail?
Which of the following is NOT a component of electronic mail?
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What is the impact of having a cache hit rate of 0.4 on total delay?
What is the impact of having a cache hit rate of 0.4 on total delay?
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What must a browser and web server maintain during their interaction?
What must a browser and web server maintain during their interaction?
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What happens to the TCP connection in a non-persistent HTTP?
What happens to the TCP connection in a non-persistent HTTP?
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What is the main characteristic of persistent HTTP?
What is the main characteristic of persistent HTTP?
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If a client or server crashes during an HTTP interaction, what must be addressed?
If a client or server crashes during an HTTP interaction, what must be addressed?
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What is the first step when a user enters a URL in a non-persistent HTTP scenario?
What is the first step when a user enters a URL in a non-persistent HTTP scenario?
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When a client receives a response message containing an HTML file, what happens next?
When a client receives a response message containing an HTML file, what happens next?
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What indicates a successful establishment of a TCP connection between client and server?
What indicates a successful establishment of a TCP connection between client and server?
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What is the primary function of SMTP in mail protocols?
What is the primary function of SMTP in mail protocols?
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Which of the following best describes IMAP?
Which of the following best describes IMAP?
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During the authorization phase in the POP3 protocol, what is the purpose of the client command 'user'?
During the authorization phase in the POP3 protocol, what is the purpose of the client command 'user'?
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Which command in the POP3 protocol is used to delete a message?
Which command in the POP3 protocol is used to delete a message?
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What does the server response '+OK' indicate in the POP3 protocol?
What does the server response '+OK' indicate in the POP3 protocol?
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What distinguishes IMAP from POP in mail protocols?
What distinguishes IMAP from POP in mail protocols?
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In the context of email protocols, what does the command 'list' do in POP3?
In the context of email protocols, what does the command 'list' do in POP3?
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Which of the following is NOT a feature of the POP protocol?
Which of the following is NOT a feature of the POP protocol?
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Which HTTP-based service is mentioned in the context of email access protocols?
Which HTTP-based service is mentioned in the context of email access protocols?
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What does the status code 200 indicate in an HTTP response?
What does the status code 200 indicate in an HTTP response?
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What response can be expected when the server responds with a 404 status code?
What response can be expected when the server responds with a 404 status code?
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Which HTTP status code should be used when a requested object has permanently moved?
Which HTTP status code should be used when a requested object has permanently moved?
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When sending a GET request using telnet, which line is necessary for the request to be complete?
When sending a GET request using telnet, which line is necessary for the request to be complete?
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What occurs when a server sends a 400 Bad Request status code?
What occurs when a server sends a 400 Bad Request status code?
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How do you establish a TCP connection to a web server for HTTP requests?
How do you establish a TCP connection to a web server for HTTP requests?
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What must you do after typing in the GET HTTP request in telnet?
What must you do after typing in the GET HTTP request in telnet?
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What is indicated by the status code 505 in an HTTP response?
What is indicated by the status code 505 in an HTTP response?
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What would typically be included following a 301 Moved Permanently status code?
What would typically be included following a 301 Moved Permanently status code?
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The average request rate from browsers to origin servers is 15 requests per second.
The average request rate from browsers to origin servers is 15 requests per second.
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In a caching scenario with a 1.54 Mbps access link, the access link utilization is 100%.
In a caching scenario with a 1.54 Mbps access link, the access link utilization is 100%.
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Increasing the access link speed is a cost-effective solution in every situation.
Increasing the access link speed is a cost-effective solution in every situation.
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The LAN utilization is 15% in the given caching example.
The LAN utilization is 15% in the given caching example.
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Total delay in a network is the sum of Internet delay, access delay, and LAN delay.
Total delay in a network is the sum of Internet delay, access delay, and LAN delay.
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An IP address and port number are sufficient for uniquely identifying a process running on a host.
An IP address and port number are sufficient for uniquely identifying a process running on a host.
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File transfer applications require 100% reliable data transfer.
File transfer applications require 100% reliable data transfer.
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UDP provides flow control, making it suitable for applications requiring low latency.
UDP provides flow control, making it suitable for applications requiring low latency.
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Web document applications require no data loss and are considered elastic in terms of throughput.
Web document applications require no data loss and are considered elastic in terms of throughput.
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Real-time audio and video applications can tolerate some loss of data.
Real-time audio and video applications can tolerate some loss of data.
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TCP is characterized as an unreliable transport protocol that does not require connection setup.
TCP is characterized as an unreliable transport protocol that does not require connection setup.
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Interactive games require low delays to be effective and can function with few kilobits per second of throughput.
Interactive games require low delays to be effective and can function with few kilobits per second of throughput.
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DNS operates as a centralized database for all hostname to IP address translations.
DNS operates as a centralized database for all hostname to IP address translations.
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If a local name server cannot resolve a name, it contacts a root name server.
If a local name server cannot resolve a name, it contacts a root name server.
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Mail server aliasing involves using one canonical name to represent multiple mail servers.
Mail server aliasing involves using one canonical name to represent multiple mail servers.
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Load distribution in DNS helps scale the system by mapping a single name to multiple IP addresses.
Load distribution in DNS helps scale the system by mapping a single name to multiple IP addresses.
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A distant centralized database is preferred for efficient DNS operation.
A distant centralized database is preferred for efficient DNS operation.
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Root DNS servers are only contacted when a local name server has the IP address already cached.
Root DNS servers are only contacted when a local name server has the IP address already cached.
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The process for obtaining the IP address of a domain involves multiple queries to different DNS servers.
The process for obtaining the IP address of a domain involves multiple queries to different DNS servers.
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Traffic volume can lead to performance issues if DNS does not utilize load distribution.
Traffic volume can lead to performance issues if DNS does not utilize load distribution.
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An authoritative name server is contacted only if the root server knows the name mapping.
An authoritative name server is contacted only if the root server knows the name mapping.
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In a client-server approach, the time to distribute a file to N clients increases linearly in N.
In a client-server approach, the time to distribute a file to N clients increases linearly in N.
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The server must upload at least two copies of the file in a P2P approach to ensure distribution.
The server must upload at least two copies of the file in a P2P approach to ensure distribution.
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The maximum upload rate is the sum of the server upload rate and the sum of all peers' upload capacities.
The maximum upload rate is the sum of the server upload rate and the sum of all peers' upload capacities.
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The time required to send one copy of a file is calculated as $F/us$.
The time required to send one copy of a file is calculated as $F/us$.
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In a client-server model, each client's minimum download time depends on their upload rate.
In a client-server model, each client's minimum download time depends on their upload rate.
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In the P2P distribution method, the time to distribute to N clients can be calculated using $DP2P > max{F/us,F/dmin,NF/(us + Sui}$.
In the P2P distribution method, the time to distribute to N clients can be calculated using $DP2P > max{F/us,F/dmin,NF/(us + Sui}$.
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Client download times in a P2P approach are independent of the download rates of the peers.
Client download times in a P2P approach are independent of the download rates of the peers.
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The server needs to send multiple copies sequentially in a client-server approach to all clients.
The server needs to send multiple copies sequentially in a client-server approach to all clients.
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The aggregate download capability of clients in a P2P system can decrease overall distribution time.
The aggregate download capability of clients in a P2P system can decrease overall distribution time.
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Match the following concepts related to caching with their explanations:
Match the following concepts related to caching with their explanations:
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Match the following network performance issues with their consequences:
Match the following network performance issues with their consequences:
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Match the following types of caching scenarios with their potential benefits:
Match the following types of caching scenarios with their potential benefits:
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Match the following average rates in the caching example with their definitions:
Match the following average rates in the caching example with their definitions:
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Match the following network elements with their descriptions:
Match the following network elements with their descriptions:
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Match the following application protocols with their primary usage:
Match the following application protocols with their primary usage:
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Match the following HTTP status codes with their meanings:
Match the following HTTP status codes with their meanings:
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Match the following application types with their corresponding transport protocols:
Match the following application types with their corresponding transport protocols:
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Match the following protocols with their layer in the OSI model:
Match the following protocols with their layer in the OSI model:
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Match the following application characteristics with their descriptions:
Match the following application characteristics with their descriptions:
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Match the following services with their reference protocols:
Match the following services with their reference protocols:
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Match the following web page components with their types:
Match the following web page components with their types:
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Match the following types of HTTP connections with their characteristics:
Match the following types of HTTP connections with their characteristics:
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Match the steps of a non-persistent HTTP request with their sequence:
Match the steps of a non-persistent HTTP request with their sequence:
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Match the following protocols with their roles:
Match the following protocols with their roles:
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Match the types of content with their associated HTTP methods:
Match the types of content with their associated HTTP methods:
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Match the following concepts related to efficiency in HTTP with their explanations:
Match the following concepts related to efficiency in HTTP with their explanations:
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Match the components of a typical HTTP transaction with their order:
Match the components of a typical HTTP transaction with their order:
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Match the following causes of state inconsistencies in HTTP with their descriptions:
Match the following causes of state inconsistencies in HTTP with their descriptions:
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Match the following networking layers with their appropriate functions:
Match the following networking layers with their appropriate functions:
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Match the following HTTP response status codes with their meanings:
Match the following HTTP response status codes with their meanings:
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Match the following terms related to HTTP requests with their descriptions:
Match the following terms related to HTTP requests with their descriptions:
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Match the following commands with their function in an HTTP interaction using telnet:
Match the following commands with their function in an HTTP interaction using telnet:
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Match the following HTTP status codes with their situations:
Match the following HTTP status codes with their situations:
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Match the following HTTP request components with their descriptions:
Match the following HTTP request components with their descriptions:
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Match the following HTTP client actions with their sequence:
Match the following HTTP client actions with their sequence:
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Match the following HTTP version phrases with their appropriate codes:
Match the following HTTP version phrases with their appropriate codes:
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Match the following outcomes with their corresponding status codes:
Match the following outcomes with their corresponding status codes:
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Match the following telnet commands with their action:
Match the following telnet commands with their action:
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Study Notes
Chapter 2: Application Layer
- The chapter outlines the fundamentals of application layer protocols in computer networking.
- PowerPoint slides are freely available for educational purposes.
- Users are asked to mention the source and copyright when using or posting the slides online.
- The goal is to understand protocols used in popular applications, their implementation, transport layer service models, client-server and peer-to-peer paradigms, and how to create network applications with a socket API.
- Various network applications such as email, web browsing, messaging, remote login, file sharing, games, and streaming video are discussed.
- Applications are built on top of end systems without the need for software on network core devices.
- Two common application architectures are described; client-server and peer-to-peer(P2P).
- Client-server architecture is characterized by always-on servers with persistent IP addresses and clients that may be intermittently connected with dynamic IP addresses. They do not communicate directly with each other.
- For P2P applications there is no always-on server. End systems act as both client and server and communicate directly. It is self-scalable and involves complex management.
- Processes within a host communicate via inter-process communication(IPC) defined by the operating system. Hosts communicate by exchanging messages.
- Sockets are used as analogous to doors, messages are sent to a socket at the receiving process.
- Applications need identifiers (IP address and port numbers) to properly receive messages from hosts.
Second Topic Subtitle
- Web and HTTP:
- Web pages are composed of multiple objects (HTML, images, applets, audio).
- The base HTML file references other objects.
- URLs are used to address objects.
- HTTP is a hypertext transfer protocol for Web applications.
- It uses TCP, client requests objects, the server sends the objects in response.
Third Topic Subtitle
- HTTP overview (continued);
- HTTP is 'stateless'
- The server does not retain information about past client requests.
- Different types of HTTP connections exist, non-persistent and persistent. The persistent connection allows multiple objects to be sent over a single TCP connection.
- HTTP request messages have a request line (GET, POST, HEAD commands), headers, and a blank line between header and body.
- HTTP response messages comprise a status line, headers, and a blank line separating headers from the body.
- Some HTTP response status codes are 200 OK, 301 Moved Permanently, 400 Bad Request, 404 Not Found, 505 HTTP Version Not Supported.
Fourth Topic Subtitle
- Uploading form input:
- POST method uploads form inputs to the server within the entity body.
- URL method uses GET uploads input in the URL field of the request line.
Fifth Topic Subtitle
- Method Types
- HTTP/1.0 supports GET, POST, and HEAD methods.
- HTTP/1.1 builds on 1.0, adding PUT and DELETE. Methods specify types of actions to be performed on the requested resource.
Sixth Topic Subtitle
- Cookies
- cookies are used by web sites for session state management, authorization, shopping carts, and recommendations, and other features.
- Cookies have four components: a header line in the response message, a header line in the request message, a cookie file stored on the user's host, and a backend database.
Seventh Topic Subtitle
- Web Caches (Proxy server)
- Caches assist in returning client requests without involving the origin server, reducing response time and traffic.
- Typical caches are installed through ISP.
Eighth Topic Subtitle
- Conditional GET
- Caches can copy content and specify date, which helps in determining whether a cached copy is up to date.
- If-Modified-Since: is used to check if a cached version is up to date; if not updated, the server returns a "304 Not Modified" code instead of the object.
Ninth Topic Subtitle
- FTP: File Transfer Protocol
- FTP transfers files between a remote host and a client.
- It uses a client-server model, where clients initiates the transfer.
- FTP uses separate control and data connections. The control connection manages commands and the data connection transfers the data.
Tenth Topic Subtitle
- Electronic Mail (email)
- Three major components: user agents (mail readers), mail servers, and simple mail transfer protocol (SMTP).
- SMTP handles transferring email messages between mail servers.
- The SMTP process involves three phases: handshaking, message transfer, and closure.
Eleventh Topic Subtitle
- Mail Access Protocols
- Mail access protocols (POP3, IMAP) are used by mail clients to retrieve mail from mail servers. POP3 downloads and deletes, while IMAP keeps messages on the server with additional features for managing message organization.
Twelfth Topic Subtitle
- Socket Programming
- Sockets are used in client/server applications to facilitate communication.
- UDP sockets provide unreliable datagram transfer, while TCP sockets provide reliable byte-stream transfer. UDP requires no handshaking, uses IP destination addresses and port# which is useful for broadcasting, while TCP requires handshaking between client and server for a connection to be established before data transfer.
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Description
Test your knowledge on essential networking concepts such as conditional GET requests in HTTP, FTP control connections, and the effects of cache hit rates on data transfer. This quiz challenges your understanding of electronic mail components and total delay implications in network communications.