PowerPoint Presentation

[Virtual Presenter] Welcome to our presentation on "Network Protocols". In this session, we will explore the fundamental concepts and protocols used in computer networking. We will start by examining some of the most widely used network protocols, including HTTP, DNS, DHCP, FTP, and more. Let's dive right in and learn about these essential technologies..

[Audio] The application layer provides services to applications running on top of it, including functions such as email, file transfer, and remote login..

[Audio] The presentation covers various protocols used in computer networks, including the Hypertext Transfer Protocol, which enables communication between web browsers and servers. The Domain Name System translates domain names into IP addresses, allowing easy access to websites. The Dynamic Host Control Protocol assigns IP addresses dynamically to devices on a network. The Simple Mail Transfer Protocol facilitates email communication through POP3, IMAP, and MIME. File Transfer Protocol allows files to be transferred over a network using FTP. TELNET provides remote access to computers, while the Simple Network Management Protocol monitors and manages network devices..

[Audio] Port numbers are used by application layer protocols to identify specific processes running on a computer. These port numbers range from 0 to 65535..

[Audio] HTTP is a protocol primarily used to access data on the World Wide Web. It operates over a bidirectional byte stream, typically using TCP. Clients send requests to servers, which respond with corresponding responses. These requests and responses are encoded in text. Notably, HTTP is a stateless protocol, meaning that servers do not maintain any information about previous client requests. Furthermore, HTTP utilizes the services of TCP on well-known port 80..

[Audio] HTTP is a protocol used to access data on the World Wide Web. It enables the transfer of various types of data, including plain text, hypertext, audio, and video. This protocol is efficient, allowing rapid jumps between documents. As a connectionless protocol, HTTP clients initiate requests and wait for responses from servers. The connection between client and server exists only during the request and response time..

[Audio] HTTP is an application layer protocol that enables communication between web clients and servers. These clients and servers are application programs that perform tasks such as retrieving web pages, sending and receiving emails, and transferring files..

[Audio] In the application layer, the Hypertext Transfer Protocol, or HTTP, operates. The client and server communicate by sending messages and data without being concerned with the underlying communication network. This ion enables efficient and flexible communication between devices..

[Audio] In an HTTP transaction, the client initiates the process by sending a request to the server. This request is then processed by the server, which responds with a corresponding reply. Notably, HTTP is a stateless protocol, meaning that the server does not retain any information about previous interactions with the client. This fundamental characteristic enables efficient communication between clients and servers, allowing multiple requests to be handled independently..

[Audio] The HTTP protocol defines two primary types of messages: requests and responses. A request is sent by a client to initiate communication with a server, while a response is sent by the server to provide information or perform an action. This figure illustrates the structure of both request and response messages, highlighting the key components that facilitate effective communication between clients and servers..

[Audio] The HTTP Request and Response status is composed of three main components. The HTTP Request type specifies the action to be performed on the requested resource, and it can be one of several options such as GET, PUT, POST, HEAD, or OPTIONS. The HTTP version has evolved over time from HTTP/0.9 to HTTP/1.1 and now HTTP/2.0. The status code indicates the outcome of the request, with a status code of 200 indicating that the request was successfully processed, resulting in an OK response..

[Audio] The Uniform Resource Locator, or URL, is a standardized way of identifying and accessing resources on the internet. To access a document online, a client requires an address, which is facilitated through the concept of URL. The URL consists of four essential components: method, host computer, port, and path. These elements work together to provide a unique identifier for the resource being accessed..

[Audio] A Uniform Resource Locator, commonly referred to as a URL, consists of several key elements. The method specifies the protocol used to retrieve a document from a server, usually HTTP. The host is the computer where the information is stored, which may have an alias name starting with "www." The port is an optional field providing additional server information. The path is the actual location of the file being retrieved, comprising directories, subdirectories, and files separated by forward slashes..

[Audio] HTTP request methods are used to interact with web servers. These methods are used to send requests to the server and receive responses. Some common built-in HTTP request methods include GET, POST, PUT, DELETE, HEAD, OPTIONS, CONNECT, and TRACE. Each method has its own specific use case and is used to perform different actions on the server..

[Audio] The built-in HTTP request methods comprise GET, HEAD, POST, and PATCH. Each method has a distinct function. The GET method retrieves a representation of a resource, yielding a JSON response accompanied by a 200 OK status code. In instances where the sought-after resource is absent, a 404 NOT FOUND or 400 BAD REQUEST status code might be returned instead. The HEAD method is analogous to GET, but merely transmits the status line and header section. The POST method is generally employed to generate novel resources, creating subordinate resources relative to a parent resource. Lastly, the PATCH method alters existing resources, necessitating solely the alterations to be incorporated within the request rather than the full resource..

[Audio] HTTP request methods are built-in features of the protocol that allow developers to interact with web servers in different ways. There are five main types of HTTP request methods: PUT, DELETE, TRACE, CONNECT, and OPTIONS. Each method serves a unique purpose. PUT replaces existing data on a server with new data. DELETE removes data from a server. TRACE tests the path of a message between a client and a server. CONNECT establishes a connection between a client and a server. OPTIONS describes the available communication options for a server. These methods provide flexibility and control when interacting with web servers..

[Audio] HTTP status codes are issued by servers in response to client requests. The first digit of these codes categorizes them into five standard classes of responses. These classifications are maintained by the Internet Assigned Numbers Authority, which keeps an official registry of all HTTP status codes..

[Audio] HTTP status codes can be categorized into five main groups, which provide information about the outcome of a request. A 1xx status code indicates that the request has been received and processing continues. A 2xx status code signifies that the request was successfully received, understood, and accepted. In contrast, a 3xx status code signals that further action is required to complete the request. A 4xx status code denotes a client error, where the request contains bad syntax or cannot be fulfilled. Finally, a 5xx status code represents a server error, where the server failed to fulfill an apparently valid request..

[Audio] HTTP connections can be categorized into two types: non-persistent and persistent. Non-persistent connections require a total time of 2RTT plus file transmission time. This type of connection is utilized for transmitting a single object. Following the client receives the object, the connection is instantly terminated. Conversely, persistent connections guarantee the transfer of multiple objects over a single connection..

[Audio] In a non-persistent HTTP connection, the total time taken is calculated by adding two round-trip times and the file transmission time. The initial round-trip time establishes the connection between the server and client, while the second round-trip time requests and returns the object. This scenario represents a single object transmission. Once the client receives the object, the connection is terminated. In contrast, a persistent connection enables the transfer of multiple objects over a single connection..

[Audio] When a persistent connection is established, the server maintains the connection open after sending a response. This allows multiple objects to be transferred over a single connection, reducing the overall round-trip time. To ensure the connection remains active, TCP keep-alive packets are periodically sent to prevent timeouts. As a result, subsequent HTTP messages can be exchanged between the server and client using the same open connection..

[Audio] In this scenario, we have two types of persistent HTTP connections: non-pipelined and pipelined. A non-pipelined connection requires the client to wait until the previous request has been acknowledged by the server before sending a new request. On the other hand, a pipelined connection allows the client to send multiple requests to the server without waiting for each request to be processed and acknowledged. This increases the speed and efficiency of data transmission over the internet..

[Audio] HTTP connections and requests can occur in different ways. There are three types of connections and requests. First, multiple connections and sequential requests are shown. Each request requires a new connection to be established. Second, a persistent connection and sequential requests are demonstrated. The same connection remains open throughout the sequence of requests. Third, a persistent connection and pipelined requests are illustrated. In this case, multiple requests are sent over the same connection, but they are processed by the server in a pipeline fashion..

[Audio] HTTP connections can either be non-persistent or persistent. In a non-persistent connection, the server closes the connection after sending a response, whereas in a persistent connection, the server keeps the connection open for multiple requests. This allows for multiple objects to be transferred over a single connection. HTTP version 1.1 specifies a persistent connection by default, while HTTP version 1.0 requires a new connection for each request-response pair. Examples of applications that use non-persistent connections include Gmail, which remains connected even when the application is closed, while banking websites typically terminate the connection once the user logs off..

[Audio] HTTP caching is a technique used to store copies of resources and serve them back when requested. When a web cache has a requested resource in its store, it intercepts the request and returns a copy of the stored resource instead of re-downloading it from the originating server. This approach improves load performance by reducing unnecessary network requests..

[Audio] The Domain Name System, also known as DNS, plays a crucial role in mapping IP addresses with domain names. This process enables users to access websites and online resources using easy-to-remember domain names instead of complex IP addresses. For instance, when accessing Facebook, the DNS system translates the domain name 'facebook.com' into the corresponding IP address '69.63.176.13'..

[Audio] TCP/IP protocols rely on IP addresses to identify entities connected to the internet. However, humans find it more convenient to use domain names instead of numerical addresses. This necessitates a system capable of mapping names to addresses or vice versa. To ensure unambiguity, names assigned to machines must be chosen from a controlled namespace where the binding between names and IP addresses is maintained. A namespace that maps each address to a unique name can be structured in either a flat or hierarchical manner..

[Audio] The Domain Name System uses the services of User Datagram Protocol using the well-known port 53, allowing it to efficiently communicate with other devices on the network. The DNS name space comprises domain resource records and name servers. A real-world analogy is a phone book, where one can easily find information by searching for a person's name rather than their phone number. For instance, the IP address 3.1.234.34 corresponds to the domain name cricinfo. Similarly, finding information about the IP address 52.19.167.6 can be achieved by looking up its corresponding domain name..

[Audio] The Domain Name System plays a crucial role in the functioning of the internet. It serves as a unique identifier for websites, enabling users to access specific resources online. The server's role is to store web pages and cache them, typically done by the Internet Service Provider. This process enables faster loading times and improved overall performance..

[Audio] When a DNS client requests a hostname like "example.com", the process begins. The client sends a request to a DNS resolver, which searches for the corresponding IP address. The resolver starts its search at the root DNS server, then moves down the hierarchy to top-level domain servers, until it finds the authoritative name server for "example.com". Once found, the resolver retrieves the IP address and related information, and returns it to the client. With the correct IP address in hand, the client can establish a direct connection to the server..

[Audio] The internet domain name space can be divided into several levels, with each level representing a different type of domain. At the topmost level, we have generic top-level domains such as com, org, net, and edu. These domains are used by organizations and individuals worldwide..

[Audio] The DNS name space is divided into zones, which are logical groupings of domain names. These zones are used to organize and manage domain names in a hierarchical manner..

[Audio] The Domain Name System, or DNS, uses various types of resource records to store information about domain names. These records can be categorized into three main groups: forward lookup records, reverse lookup records, and other records. Forward lookup records map hostnames to IP addresses, while reverse lookup records map IP addresses to hostnames. Other records include those used for mail exchange, name servers, and other purposes..

[Audio] When a resolver needs to look up a remote name, it initiates a process involving multiple steps. The process begins with the resolver checking its local cache for the desired domain name. If the name is not found, the resolver sends a request to a top-level domain server. The server then checks its own cache and if the name is still not found, it forwards the request to another server until the actual IP address is obtained. Finally, the resolver receives the IP address from the autoreactive server and updates its local cache. This entire process involves ten steps, which are illustrated in this figure..

[Audio] HTTP is a non-persistent connection protocol, which means that each request from a client to a server is independent of previous requests. This allows multiple clients to share the same connection to the server. In contrast, persistent connections allow a single connection to remain open between the client and server for multiple requests. HTTP version 1.0 uses non-persistent connections, whereas HTTP version 1.1 supports both non-persistent and persistent connections. The port number used for HTTP is 80. Similarly, DNS uses UDP as its transport protocol, with a port number of 53. Finally, HTTP request types include GET, PUT, POST, HEAD, and OPTIONS. All these types are true..

[Audio] The process of mapping a name to an address or an address to a name is known as name-address resolution. This resolution can occur through two methods: recursive resolution and iterative resolution..

[Audio] When a host wants to access a website, it needs to obtain the IP address associated with that website's domain name. The host sends a query message to the DNS resolver, which searches for the corresponding IP address in its own cache memory. If the IP address is not found, the resolver will forward the query to the root server, which then forwards the query to the top-level domain server, such as the.com server. The top-level domain server checks if the IP address exists in its database and returns the IP address to the host if found. If not, the resolver will continue searching until the IP address is found. This recursive resolution process ensures that the host obtains the correct IP address for the website it wants to access..

[Audio] In this process, we map a name to an address or an address to a name, which is known as name-address resolution. This is a crucial step in ensuring that data packets reach their intended destination on the internet..

[Audio] When a domain name system resolver needs to resolve a top-level domain, it may need to send multiple queries to different servers. This process is known as iterative resolution. During this process, the resolver sends a query message to one server, and if the response indicates that the requested information is not available on that server, the resolver will then send the query to another server. This iterative process continues until the resolver finds the required information or reaches the root domain..

[Audio] The iterative resolution process breaks down complex problems into smaller, manageable parts, and addresses each part iteratively until the issue is resolved. This approach refines our understanding of the problem and develops targeted solutions. Working through each step ensures that all aspects of the issue are thoroughly addressed, leading to a more effective and efficient resolution..

[Audio] The difference between recursive and iterative resolution lies in their approach to solving problems. Recursive resolution involves breaking down complex problems into smaller sub-problems until a solution is found. This process is repeated recursively until the problem is solved. On the other hand, iterative resolution involves repeating a set of instructions until a solution is found. In this method, the same steps are performed repeatedly until the desired outcome is achieved..

[Audio] Both Query and Response messages in the Domain Name System (DNS) have the same header format. This format consists of 12 bytes, which include various fields. These fields provide essential information such as identification, flags, questions, answer resource records, authority resource records, and additional resource records. The header serves as a crucial part of the DNS query and response process, allowing for efficient communication between clients and servers..

[Audio] The DNS protocol employs two fundamental modes of communication: queries and responses. Both formats exhibit a consistent structure, comprising multiple sections. These sections encompass identification, flags, questions, answer records, authority records, and additional records. This uniformity facilitates efficient processing and interpretation of DNS messages..

[Audio] This presentation is a culmination of our efforts over the past few months. We have worked diligently to ensure that all necessary information is included in this report..

[Audio] The presentation continues with the next topic, which is related to the previous one. This information is part of the comprehensive report on the project's progress. We will now discuss the key findings and recommendations from the analysis..

[Audio] Flag bits are used to define the type of DNS message and provide additional information about the message. They are used in both query and response messages. The flags include QR, OpCode, AA, TC, RD, RA, Reserved, and rCode. Each flag has a specific meaning and function, such as defining the type of message, indicating whether the response is authoritative, or showing the status of the error in the response..

[Audio] The header format used in this presentation provides additional information beyond the standard header. This extra detail includes the unit number, course name, presentation title, semester, academic year, and date..

[Audio] Question Records are used in the question section of the query and response messages. Resource Records are used in the answer, authoritative, and additional information sections of the response message..

[Audio] Resource records are used to store information about network resources such as domain names, IP addresses, and mail servers. This format is essential for understanding how DNS works..

[Audio] We are grateful to each and every one of you for your attention and engagement throughout this session. Your participation has been invaluable, and we appreciate your time and consideration..