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Questions and Answers
What are the two main types of HTTP messages?
What are the two main types of HTTP messages?
HTTP request and HTTP response.
What does the request line of an HTTP request message typically include?
What does the request line of an HTTP request message typically include?
Method, URL, and version.
What characters indicate the end of header lines in an HTTP request?
What characters indicate the end of header lines in an HTTP request?
Carriage return (
) followed by line feed (
).
What is the primary purpose of the POST method in an HTTP request?
What is the primary purpose of the POST method in an HTTP request?
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What does the HEAD method do in HTTP requests?
What does the HEAD method do in HTTP requests?
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What type of format is the HTTP request message primarily based on?
What type of format is the HTTP request message primarily based on?
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In an HTTP request, what do header lines typically consist of?
In an HTTP request, what do header lines typically consist of?
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What is the primary benefit of HTTP/2's frame interleaving over HTTP/1.1?
What is the primary benefit of HTTP/2's frame interleaving over HTTP/1.1?
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How does the shift from TCP in HTTP/2 to UDP in HTTP/3 influence data transmission?
How does the shift from TCP in HTTP/2 to UDP in HTTP/3 influence data transmission?
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What are the implications of using multiple parallel TCP connections in HTTP/2?
What are the implications of using multiple parallel TCP connections in HTTP/2?
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In what way does HTTP/3 improve security compared to HTTP/2?
In what way does HTTP/3 improve security compared to HTTP/2?
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Why might developers prefer HTTP/3 over HTTP/2 for new applications?
Why might developers prefer HTTP/3 over HTTP/2 for new applications?
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How can the access link utilization be computed in the context of the provided scenarios?
How can the access link utilization be computed in the context of the provided scenarios?
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What is the average request rate from browsers to the origin servers?
What is the average request rate from browsers to the origin servers?
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What does the term RTT stand for, and how is it relevant in this scenario?
What does the term RTT stand for, and how is it relevant in this scenario?
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In terms of performance, what could be expected if a web cache is installed?
In terms of performance, what could be expected if a web cache is installed?
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What is the size of the web object being transmitted in bits?
What is the size of the web object being transmitted in bits?
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Discuss the trade-offs between cost and performance when choosing to buy a faster access link vs. installing a web cache.
Discuss the trade-offs between cost and performance when choosing to buy a faster access link vs. installing a web cache.
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What impact does LAN utilization of .0015 have on the overall network performance?
What impact does LAN utilization of .0015 have on the overall network performance?
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What is the primary function of the 'GET' request in HTTP as demonstrated in the example?
What is the primary function of the 'GET' request in HTTP as demonstrated in the example?
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Explain the purpose of a 'first party' cookie.
Explain the purpose of a 'first party' cookie.
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Describe the role of 'third party' cookies in web browsing.
Describe the role of 'third party' cookies in web browsing.
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What does the term 'referrer' signify in the HTTP request structure provided?
What does the term 'referrer' signify in the HTTP request structure provided?
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How do cookies contribute to user experience on websites like nytimes.com?
How do cookies contribute to user experience on websites like nytimes.com?
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What HTTP method can be inferred to be used for displaying the composed page after fetching resources?
What HTTP method can be inferred to be used for displaying the composed page after fetching resources?
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Identify the sequence of HTTP actions from the content when displaying a NY Times web page.
Identify the sequence of HTTP actions from the content when displaying a NY Times web page.
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What implications do cookies from both first and third party have on user privacy?
What implications do cookies from both first and third party have on user privacy?
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What does the PUT method do in an HTTP request?
What does the PUT method do in an HTTP request?
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How does a GET request send user data to the server?
How does a GET request send user data to the server?
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Identify a key feature of the HTTP response status line.
Identify a key feature of the HTTP response status line.
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What does the status code '200 OK' signify in an HTTP response?
What does the status code '200 OK' signify in an HTTP response?
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What does the status code '404 Not Found' indicate?
What does the status code '404 Not Found' indicate?
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State the significance of the 'Location:' field in an HTTP response.
State the significance of the 'Location:' field in an HTTP response.
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Define what a '400 Bad Request' status code means.
Define what a '400 Bad Request' status code means.
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What does the HTTP status code '505 HTTP Version Not Supported' signify?
What does the HTTP status code '505 HTTP Version Not Supported' signify?
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Explain the role of the Domain Name System (DNS) in internet communication.
Explain the role of the Domain Name System (DNS) in internet communication.
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What are the implications of using a centralized DNS system?
What are the implications of using a centralized DNS system?
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How does the DNS hierarchy contribute to its resilience?
How does the DNS hierarchy contribute to its resilience?
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Why is it necessary to have aliasing services in DNS?
Why is it necessary to have aliasing services in DNS?
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Discuss the importance of application-layer protocols like DNS in network applications.
Discuss the importance of application-layer protocols like DNS in network applications.
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What challenges arise from the complexity at the network's edge in name resolution?
What challenges arise from the complexity at the network's edge in name resolution?
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Describe mail server aliasing and its significance in DNS.
Describe mail server aliasing and its significance in DNS.
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What does the volume of DNS queries indicate about its operation in the internet ecosystem?
What does the volume of DNS queries indicate about its operation in the internet ecosystem?
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Flashcards
Round Trip Time (RTT)
Round Trip Time (RTT)
The amount of time it takes for a packet to travel from the browser to the origin server and back.
Data Rate
Data Rate
The rate at which data is transmitted from the origin server to the browser.
Web Cache
Web Cache
A device that stores copies of frequently accessed web objects to reduce the load on the origin server.
Access Link Utilization
Access Link Utilization
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LAN Utilization
LAN Utilization
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End-to-End Delay
End-to-End Delay
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Caching
Caching
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Faster Access Link
Faster Access Link
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Cookie
Cookie
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First-party cookie
First-party cookie
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Third-party cookie
Third-party cookie
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Fetching a HTML file
Fetching a HTML file
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HTTP GET request
HTTP GET request
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HTTP Reply
HTTP Reply
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Composing a web page
Composing a web page
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Ad network (e.g., AdX.com)
Ad network (e.g., AdX.com)
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GET method (for sending data to server)
GET method (for sending data to server)
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PUT method
PUT method
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PUT method for replacing files
PUT method for replacing files
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HTTP status line
HTTP status line
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HTTP Response Status Code
HTTP Response Status Code
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200 OK
200 OK
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301 Moved Permanently
301 Moved Permanently
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400 Bad Request
400 Bad Request
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HTTP Request Message
HTTP Request Message
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HTTP GET Method
HTTP GET Method
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HTTP HEAD Method
HTTP HEAD Method
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HTTP Request Line
HTTP Request Line
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Header Lines
Header Lines
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Entity Body
Entity Body
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HTTP POST Method
HTTP POST Method
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Carriage Return and Line Feed (CR/LF)
Carriage Return and Line Feed (CR/LF)
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HTTP
HTTP
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HTTP/2 & HOL Blocking
HTTP/2 & HOL Blocking
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HTTP/3 over UDP
HTTP/3 over UDP
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HTTP/3 Advantages
HTTP/3 Advantages
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Application Layer
Application Layer
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What is the Domain Name System (DNS)?
What is the Domain Name System (DNS)?
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How does DNS work?
How does DNS work?
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Why is DNS decentralized?
Why is DNS decentralized?
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What is the structure of DNS?
What is the structure of DNS?
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What happens when you access a website?
What happens when you access a website?
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What other services does DNS provide?
What other services does DNS provide?
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Why is DNS important?
Why is DNS important?
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What is the significance of DNS?
What is the significance of DNS?
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Study Notes
Computer Networking
- A field encompassing the study of networked computer systems
- Introduces fundamental concepts and practical applications
Application Layer
- Serves as the interface between users and network applications, allowing individuals to interact seamlessly with various software tools and services available over the internet. This interface is essential as it translates user actions into network requests, ensuring that data flows smoothly between users and the applications they are utilizing.
- Facilitates communication between applications by employing specific protocols and functionalities that govern how data is transmitted, enabling interoperability and consistent interaction. This ensures that different applications can communicate effectively, even if they were developed independently and are operated on different systems.
- Includes various applications such as web browsing, email, and video streaming, which are integral to the daily activities of internet users. Each of these applications relies on the application layer to provide the necessary functions for sending and receiving information, whether it be loading web pages, exchanging messages, or streaming media content.
- The top layer of the TCP/IP model, which is crucial for enabling the user-oriented functionalities of the internet. This layer works directly with end-user applications and is responsible for ensuring that the user requirements are met in terms of data transfer and application performance.
- Involves network application protocols, conceptual and implementation aspects, transport-layer service models, client-server architectures, and peer-to-peer paradigms. Each of these elements plays a role in shaping how applications interact and share resources across networks, influencing the design and functionality of internet-based systems.
- Application-specific data is encapsulated in messages, which utilize sockets as the interface for communication between applications. Sockets are the endpoints for sending or receiving data, allowing different applications on the same or different devices to establish connections and exchange messages reliably.
- Application-layer protocols define message types, syntax, semantics, and rules for message exchange. These protocols are critical as they ensure that both sender and receiver understand the format and meaning of the messages being transmitted, thus facilitating accurate and efficient communication.
Web and HTTP
- The Web is an application layer client/server architecture
- HTTP (Hypertext Transfer Protocol): is a client-server protocol for communication
- HTTP is a stateless protocol where each request is independent of previous interactions, so the server doesn't need to maintain user session state
- HTTP uses TCP for reliable data transfer. Requests and responses are typically in ASCII format, with headers containing information about the request and response bodies carrying the data.
- Two major types of HTTP connections: Non-persistent and Persistent
- Each HTTP request type serves a specific purpose within the communication process between the client and server. The GET method is utilized to request data from a specified resource and is primarily used to retrieve information without making any changes. POST, in contrast, is used to submit data to be processed, often resulting in the creation of new resources. The HEAD method functions similarly to GET but requests only the headers, not the body, to check resource availability or metadata. PUT is used for updating existing resources, while DELETE is employed to remove them. The OPTIONS method queries the server for supported HTTP methods and other options applicable to a resource, contributing to efficient and versatile interactions.
E-mail, SMTP, IMAP
- Electronic mail is a commonly used application layer protocol
- SMTP (Simple Mail Transfer Protocol): responsible for the transfer of email messages between mail servers.
- IMAP (Internet Message Access Protocol): protocol used by email clients to access emails stored on a mail server.
- E-mail systems comprise user agents (clients like Outlook email application), mail servers (for sending/receiving messages). A "message queue" acts as the intermediary between the client & server.
DNS (Domain Name System)
- System responsible for converting human-readable domain names (e.g., www.example.com) into numerical IP addresses (e.g., 192.168.1.1).
- Distributed, hierarchical database that's essential for the Internet
- Resolves names into IP addresses.
- The DNS architecture is a hierarchical and decentralized system designed to improve the efficiency and reliability of internet navigation. It consists of several types of servers, each serving a distinct purpose. Root servers are at the top of this hierarchy and play a critical role by directing traffic to the correct TLD (Top-Level Domain) servers, which handle the management of specific domain name extensions, such as .com, .org, and .net. The next level comprises authoritative servers that provide definitive answers to queries about domain names, ensuring accurate information is relayed. Additionally, local DNS servers cache responses from previous queries, thereby speeding up the resolution process and reducing the overall load on higher-level servers, enhancing the user experience significantly.
- Utilizes a hierarchical structure with distinct roles for each type of server allowing efficient name resolution.
- Caches results to improve efficiency.
- Important in large and distributed systems.
Video Streaming and CDNs
- Streaming video relies on a large network or Content Delivery Network (CDN)
- CDNs store copies of content to deliver them to multiple geographically disparate sites in advance of being requested, enabling fast access to videos when needed
- Using CDN sites distributed geographically close to clients enhances speed and reduces lag for users.
Multimedia
- Video is a sequence of images displayed at a constant frame rate
- Coding methods reduce the amount of data needed by utilizing redundancies. This reduces bandwidth usage required and increases streaming speeds.
- Constant Bit Rate (CBR) and Variable Bit Rate (VBR) are the two major variations in video encodings utilized to adapt to changes in network conditions associated with media streaming
Streaming Stored Video
- Server sends video data to the client in chunks.
- Video playback on the client is made possible through playout buffering
- Buffering mechanism handles variable network delays and delay jitter.
- Video data may be lost and needs to be retransmitted if necessary.
HTTP/2 and HTTP/3
- HTTP/2 improves on HTTP/1.1 in terms of efficiency and speed - improved transmission order and parallel requests
- HTTP/3 adds enhanced resilience through the use of the UDP protocol for more reliable streaming of data.
Application Layer Protocols
- HTTP for web access. SMTP for sending email messages. IMAP for retrieving emails. DNS for name resolution. P2P for peer-to-peer file-sharing. BitTorrent for file sharing
- Various security implementations, like cookies and SSL, for storing user data
- Key protocols are fundamental in modern networking architecture by enabling seamless communication among different systems. Each has a unique function and method of functioning while interacting with various applications such as email, streaming, and web browsing
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Description
Test your knowledge on the basics of HTTP messages and methods. This quiz covers key concepts such as request lines, header lines, and the differences between HTTP/1.1, HTTP/2, and HTTP/3. Perfect for those studying web protocols and internet communication.