Application Layer Module 15 Quiz

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Questions and Answers

What is the correct sequence of actions a browser takes when a URL is typed in?

Checks with a name server, sends a GET request, and deciphers HTML code. (correct)

Converts the URL to HTML code, sends a GET request, and formats the page.

Establishes a connection, sends a POST request, and converts the server name.

Sends a PUT request, receives the numeric IP, and requests the URL.

Which of the following protocols is considered not secure?

FTP

HTTPS

HTTP (correct)

TCP

What does the GET message in the HTTP protocol do?

Establishes a connection with the server.

Requests data from the web server. (correct)

Sends data files to the web server.

Uploads resources to the server.

What part of a URL does 'www.cisco.com' represent?

The server name Signup and view all the answers

What is the role of the name server when a URL is entered in a browser?

To translate the server name into a numeric IP address. Signup and view all the answers

Which HTTP message type is used for uploading data files to a web server?

POST Signup and view all the answers

In the context of HTTP messaging, which of the following is NOT a common message type?

JOIN Signup and view all the answers

After the browser sends a GET request, what does the server respond with?

HTML code for the requested web page. Signup and view all the answers

What is the primary purpose of the Domain Name Service (DNS)?

To convert numeric IP addresses into recognizable domain names Signup and view all the answers

Which resource record type is used to represent an end device's IPv4 address?

A Signup and view all the answers

What action does a DNS server take if it cannot resolve a name from its own records?

It queries other DNS servers for resolution Signup and view all the answers

How are DNS messages structured when sent between servers?

In a standardized format consisting of question, answer, authority, and additional information Signup and view all the answers

What type of DNS record is designated for mail exchange?

MX Signup and view all the answers

What is an example of a Fully-Qualified Domain Name (FQDN)?

<a href="http://www.cisco.com">http://www.cisco.com</a> Signup and view all the answers

Which record type is used for identifying an authoritative name server in DNS?

NS Signup and view all the answers

What occurs after a DNS server successfully resolves a name for the first time?

The address is temporarily stored for future requests Signup and view all the answers

What is the primary purpose of the Answer section in a DNS message?

To provide resource records that answer the query Signup and view all the answers

Which domain is an example of a top-level domain that indicates a non-profit organization?

.org Signup and view all the answers

What does the nslookup command primarily do?

Manually queries DNS servers to resolve a hostname Signup and view all the answers

What is the first TCP port that an FTP client uses to establish a connection with an FTP server?

21 Signup and view all the answers

Which of the following best describes the role of hierarchy in DNS?

It enables DNS servers to manage small portions of the database. Signup and view all the answers

What type of information is found in the Authority section of a DNS message?

Resource records pointing towards an authoritative server Signup and view all the answers

What is typically contained within the Additional section of a DNS message?

Supplementary resource records for additional context Signup and view all the answers

Which statement is true regarding the responsibilities of DNS servers?

A DNS server forwards requests it cannot resolve to another server. Signup and view all the answers

Study Notes

Module 15: Application Layer

This module covers the application layer, a fundamental part of network communication.
The introduction to networks v7.0 (ITN) curriculum is referenced.

15.3 Web Protocols

Web protocols facilitate communication between web browsers and servers.
The Uniform Resource Locator (URL) is a crucial element in web navigation.

Hypertext Transfer Protocol & Hypertext Markup Language

The browser interprets the URL's components: protocol (e.g., http), server name, and file name.
The browser connects to the web server using the HTTP protocol.
The server returns the requested webpage's HTML code.
The browser processes the HTML, displaying the webpage.

Step-by-step process for web page opening

Step 1: The browser interprets the URL's parts (protocol, server, filename).
Step 2: The browser queries a name server for the IP address of the server.
Step 3: The web server sends the HTML code for the requested page.
Step 4: The browser displays the formatted page.

HTTP and HTTPS

HTTP defines the message types used in web communication, including GET, POST, and PUT.
GET retrieves data, POST uploads data, and PUT uploads resources.
HTTP is not secure; HTTPS is the secure version.

15.4 IP Addressing Services

IP addressing services enable communication between devices on a network.
The Domain Name Service (DNS) converts human-readable domain names to IP addresses.
Fully Qualified Domain Names (FQDNs) are easier for users to remember than numeric addresses.
This process includes querying a name server to retrieve the IP address.

DNS Message Format

DNS servers store different resource records (e.g., A, NS, AAAA, MX).
These records contain name, address, and type information to resolve names.
When a client queries for a name, the server first checks its own records; if unsuccessful, it can query for help.
Successfully resolving names typically includes temporarily storing the numeric address.

DNS Message Format (Continued)

DNS uses a standardized message format for client queries and server responses.
This format includes sections for "Question," "Answer," "Authority," and "Additional" information.
- Question section contains the query for the name.
- Answer section provides the resource records.

DNS Hierarchy

DNS uses a hierarchical structure to organize and manage name resolution across the Internet.
Different servers maintain different parts of the data, with the root DNS servers at the apex.
Top level domains (.com, .org, .edu) constitute the hierarchical structure of the DNS.
Queries can be resolved to different servers until the address is found.

The nslookup Command

The nslookup utility allows querying DNS servers for hostname resolution.
It can help troubleshoot name resolution.
The command issues requests to DNS servers for hostname to IP address resolution.
Default DNS server is displayed.

File Transfer Protocol (FTP) enables transferring files between clients and servers.
FTP uses TCP ports 20 and 21 for data and control traffic.
Clients initiate a "control connection" to the server.
Clients use a "data connection" to exchange data.
Clients can either upload (push) or download (pull) data.

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Description

Test your knowledge on the Application Layer, specifically focusing on web protocols and the process of web page loading. This quiz is part of the Introduction to Networks v7.0 curriculum. Challenge yourself on how URLs, HTTP, and HTML interact during web communication.