IDC EXAM NOTES PDF

Explain client server model and provide with examples In the client/server model, the device requesting the information is called a client and the device responding to the request is called a server. Client and server processes are considered to be in the application layer. The client begins the exc...

Explain client server model and provide with examples In the client/server model, the device requesting the information is called a client and the device responding to the request is called a server. Client and server processes are considered to be in the application layer. The client begins the exchange by requesting data from the server, which responds by sending one or more streams of data to the client. Application layer protocols describe the design of the requests and responses between clients and servers. In addition to the actual data transfer, this exchange can require control information, such as user authentication and the identification of a data file to be transferred. One example of a client/server network is a corporate environment where employees use a company e-mail server to send, receive, and store e-mail. The e-mail client on an employee computer issues a request to the e-mail server for any unread mail. The server responds by sending the requested e-mail to the client. Describe end devices and their role in network The network devices that people are most familiar with are called end devices. All computers connected to a network that participate directly in network communication are classified as hosts. These devices form the interface between users and the underlying communication network. Some examples of end devices are: 1. Computers (workstations, laptops, file servers, and web servers) 2. Network printers 3. VoIP phones 4. Telepresence endpoints 5. Security cameras 6. Mobile handheld devices (smartphones, tablets, PDAs, and wireless debit/credit card readers and barcode scanners) 7. Sensors such as thermometers, weight scales, and other devices that will be connected to the IoE Describe Intermediary network devices and their role in network Examples of intermediary network devices are: 1. Switches and wireless access points (network access) 2. Routers (internetworking) 3. Firewalls (security) Explain TCP/IP model 1. Physical Layer (Layer 1) Function: Handles the physical connection between devices and the transmission of raw binary data (bits) over a communication medium (e.g., cables, wireless signals) Key Responsibilities: ○ Encoding and transmitting data as electrical, optical, or radio signals. ○ Ensuring physical connection reliability Examples: Ethernet, Wi-Fi, coaxial cables, fiber optics 2. Data Link Layer (Layer 2) Function: Manages direct node-to-node communication and error detection/correction in frames (data packets at this layer) Key Responsibilities: ○ Framing: Encapsulating network-layer data into frames ○ Media Access Control (MAC): Determining how devices share the communication medium ○ Error detection/correction Examples: MAC addresses, ARP (Address Resolution Protocol), Ethernet, Wi-Fi 3. Network Layer (Layer 3) Function: Handles routing and forwarding of data packets across multiple networks to reach their destination Key Responsibilities: ○ Logical addressing: Assigning IP addresses to devices ○ Routing: Determining the best path for data transmission  ○ Fragmentation and reassembly of packets Examples: IP (Internet Protocol), ICMP (Internet Control Message Protocol) 4. Transport Layer (Layer 4) Function: Ensures end-to-end communication between devices, including error checking and data flow control Key Responsibilities: ○ Segmentation and reassembly: Dividing messages into segments and reassembling them at the destination. ○ Reliable delivery: Using acknowledgments and retransmissions (in TCP). ○ Multiplexing: Allowing multiple applications to share the same network connection Examples: ○ TCP (Transmission Control Protocol) for reliable communication. ○ UDP (User Datagram Protocol) for faster, less reliable communication 5. Application Layer (Layer 5, but if you’re writing OSI, this is Layer 7) Function: Provides network services to applications and end-users Key Responsibilities: ○ Enabling user applications to interact with the network. ○ Formatting and presenting data for end-user applications Examples: ○ HTTP/HTTPS (Web browsing) ○ FTP (File Transfer Protocol) ○ SMTP (Email communication) 5. Session Layer (Layer 5 if you’re doing OSI) Function: Manages and controls the connections (sessions) between two devices. It is responsible for establishing, maintaining, and terminating communication sessions.  Key Responsibilities: ○ Session Establishment: Sets up and coordinates communication between devices ○ Synchronization: Adds checkpoints during data transfer to enable resuming in case of interruption ○ Session Termination: Gracefully ends communication once tasks are complete. Examples: ○ Remote Procedure Call (RPC) ○ Session protocols like NetBIOS, SMB (used in file sharing) 6. Presentation Layer (Layer 6 if you’re doing OSI) Function: ○ Responsible for translating data between the application layer and the network. It ensures that the data is in a format that the receiving application can understand ○ Handles data compression, encryption, and conversion. Key Responsibilities: ○ Translation: Converts data formats, such as from ASCII to EBCDIC or from JPEG to bitmap ○ Encryption/Decryption: Ensures secure data transmission by encoding and decoding data ○ Compression: Reduces the size of data for faster transmission Examples: ○ File formats (JPEG, PNG, MP3). ○ Encryption protocols (SSL/TLS for secure web communication) Explain CIAAN with examples (Network Security) Confidentiality: Data should be confidential. This means that data is only known or accessible to authorized users. ○ Examples: Encryption, VPNs, access control  Integrity: Data must have integrity. This means that the data is complete and accurate. ○ Examples: Hashing, digital signatures, version control Authentication: Data should be authentic. This means that the data should have not been tampered with in any manner. ○ Examples: MFA, biometrics, OAuth Availability: Data must be available to authorized users. This means that if the user is authorized, he or she must have full access to the data. ○ Examples: Redundant systems, DDoS protection, cloud service uptime guarantees Non-repudiation: Non-repudiation is the assurance that both parties involved in a digital transaction cannot deny that they did not make that transaction ○ Examples: Digital certificates, blockchain, email logging Explain any five TCP and UDP key differences TCP: Connection-oriented. Establishes a reliable connection between sender and receiver before transmitting data (via a three-way handshake). UDP: Connectionless. Data is sent without setting up a connection, which makes it faster but less reliable. TCP: Reliable, ensures delivery and order UDP: Unreliable, no guarantees of delivery TCP: Slower due to overhead UDP: Faster due to minimal overhead TCP: Larger (20–60 bytes) UDP: Smaller (8 bytes) TCP: Web browsing, email, file transfer UDP: Streaming, gaming, DNS queries Explain how packet switching works Data is divided into small, manageable units called packets before transmission. Each packet is assigned a header containing important metadata, such as: Source and destination IP addresses. Sequence number for reassembly. Error-checking information. Packets are sent individually and may take different routes to the destination based on network availability and efficiency. Routers analyze network conditions (e.g., traffic, availability) to determine the best path for each packet. Packets may arrive at the destination out of order or even experience loss. At the destination, packets are reassembled into the original data sequence using the sequence numbers in their headers. What are the different types of network media used for communication, and what factors should be considered when choosing the appropriate media for a network? Copper: Twisted-pair cable usually Electrical pulses used as LAN media Fiber-optic: Glass or plastic fibers in a vinyl coating Light pulses usually used for long runs in a LAN and as a trunk Wireless: Connects local users through the air Electromagnetic waves 1. The distance the media can carry the signal 2. The environment in which the media works 3. The bandwidth requirements for users 4. The cost of installation 5. The cost of connectors and compatible equipment Explain the differences between LAN and WAN LAN: A network that connects devices within a small geographical area. WAN: A network that spans large geographical areas, often worldwide. LAN: Homes, offices, or schools. WAN: Cities, countries, or continents. LAN: Owned, managed, and maintained by a single organization. WAN: Owned by ISPs, large companies LAN: Faster due to low latency and high bandwidth. WAN: Slower compared to LAN due to longer distances and more traffic. LAN: Ethernet, Wi-Fi WAN: Satellites and fiber optics. LAN: Cheaper to set up WAN: Expensive to set up Subnetting: Given the IP address 198.22.45.173/26, calculate the following: Network Address: 198.22.45.128/26 Broadcast Address: 198.22.45.191 First Usable IP Address: 198.22.45.129 Last Usable IP Address: 198.22.45.190 Range of Usable IP Addresses: 198.22.45.129 - 198.22.45.190