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Chapter 4: Transport And Application Layer, GUIDE:, FAHIM, 2.BETIANA,…
Chapter 4: Transport And Application Layer
4.2.1 Explain how the functions of the application layer, session layer, and presentation layer work together to provide network services to end user applications.
Application Layer:
:check:Closest to the end user
:check:Used to exchange data between programs running on the source and destination hpsts.
2.Presentation and Session Layer
(Fahim)
The function on presentation layer :
:check:Formating data at the source device into a compatible form for the recieving device
:check: Compressing data
:check:Encrypting data
The function on Session Layer Function
:check:Create and maintain dialogs between source and destination applications
3.TCP/IP Application Layer Protocols
(Fahim)
:check:Domain Name Server (DNS) TCP,UDP 53- Translate domain names, such as cosco.com, itno IP addressws
:check:(BOOTP) - Bootstrap Protocol - BOOTP is being superseded by DHCP
:check:Dynamic Host Configuration Protocol (DHCP) UDP client 68, server 67 - Dynamically assigns IP addresses to client stations at start-up
:check:Simple Mail Transport Protocol (SMTP) TCP 25 - Enables clients to send email to main server.
:check:Post Office Protocol (POP) TCP 110 - enables clients to retrieve email from a mail server.
:check:Internet Message Access Protocol (IMAP) TCP 143 - Enables clients to retrieve email from a mail server, maintains email on server
:check:File Transfer Protocol(FTP) TCP 20 and 21 - Reliable, connectionless file transfer protocol
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4. Client-Server Model
(Fahim)
:check:Client and server processes are considererd to be in the application layer
:check:Application layer protocols describe the format of the requests and responses between clients and servers
:check: For example, a client-server network is using an ISP's email service to send, receive and store email.
5. Peer-to-Peer Networks
(Abfis)
:check: Data can be accessed from a peer device easily without relying on a dedicated server
:check: Every device or more known as peer can work as a server and also as a client
Fahim & Abfis
6. Peer-to-Peer Applications
(Abfis)
:check: A Peer-to-Peer or P2P application lets the device to act as both a client and a server in a similar communication
:check: Each end device is required to provide a user interface and run a background service for the P2P application
7. Common P2P Applications
(Abfis)
:check:
Example of P2P network that you might know
:pen: G2
:pen: Bitcoin
:pen: BitTorrent
:pen: eDonkey
:check: There is some P2P applications that use te Gnutella protocol. Which is when every user shares whole files with each other
:check: Most P2P applications allows their user to share pieces of many file with one another at the exact same time. This is known as BitTorrent Technology
4.2.2 Explain how web and email protocols operate.
(Nurul & Grace)
Hypertext Transfer Protocol & Hypertext Markup Language
The web browser establishes a connection to thr web service running on the server when a web address or URL is typed into a web browser by using HTTP protocol.
HTTP & HTTPS
HTTP
is a request/response
3
common HTTP message type:
GET ; A client request for data
POST ; Uploads data files to web server.
PUT ; Upload resources or content to the web server
HTTPS
protocol uses encryption & authentication to secure data.
Email Protocols
3 protocol for email:
Simple Mail Transfer Protocol
(SMTP)
to send email.
Post Office Protocol
(POP)
to retrieve email.
Internet Message Access Protocol
(IMAP)
to retrieve email.
SMTP Operation
:red_flag: SMTP is used to send email
POP Operation
:red_flag: POP is used to retrieve email from a mail server.
:red_flag: Email is downloaded from the server to client and then deleted on the server.
IMAP Operation
:red_flag: IMAP is used to retrieve mail from a mail server
:red_flag: Copies of messages are downloaded from the server to the client and the original messages are stored on the server.
Packet Tracer
definition of Packet Tracer
:
a network simulation program that provides simulation, visualization, authoring, assessment, and collaboration capabiities and facilitates the teaching and learning of complex technology concepts.
File Sharing Services
File Transfer Protocol
requires 2 connections between the client and the server, one for commands and replies, the other for the actual file transfer
the client establishes the first connection to the server for control traffic using TCP port 21
the client establishes the second connection to the server for the actual data transfer using port 20
Server Message Block
is a client/server file sharing protocol
SMB file-sharing and print services have become the mainstay of Microsoft networking
clents establish a long-term connection to servers and can access the resources on the server as if the resource is local to the client host
4.2.3 Explain how DNS and DHCP operate
(
DNS Hierarchy
The DNS hierarchy, also called the domain name space, is an inverted tree structure, much like eDirectory.
The DNS tree has a single domain at the top of the structure called the root domain.
A period or dot (.) is the designation for the root domain.
The nslookup Command
Nslookup - a utility that allows a user to manually query the name servers to resolve a given host.
DNS Message Format
The server’s DNS process first looks at its own records to resolve the name.
If unable to resolve, it contacts other servers to resolve the name.
The server temporarily stores the numbered address in the event that the same name is requested again
The ipconfig /displaydns command displays all of the cached DNS entries on a Windows PC.
Dynamic Host Configuration Protocol
The Dynamic Host Configuration Protocol (DHCP) for IPv4 automates the assignment of IPv4 addresses, subnet masks, gateways, and other parameters
DHCP-distributed addresses are leased for a set period of time, then returned to pool for reuse.
DHCP is usually employed for end user devices. Static addressing is used for network devices, such as gateways, switches, servers, and printers
DHCPv6 (DHCP for IPv6) provides similar services for IPv6 clients.
Domain Name Service
Domain names convert the numeric address into a simple, recognizable name.
The DNS protocol defines an automated service that matches resource names with the required numeric network address
DHCP Operation
DHCP works in a client/server mode and operates like any other client/server relationship
When a PC connects to a DHCP server, the server assigns or leases an IP address to that PC, which enables The PC, connects to the network with that leased IP address until the lease expires
Betiana
GUIDE:
Insert ur colour for ur subtopic
FAHIM
2.BETIANA
ABFIS
NURUL
GRACE
