Network+ Exam study

Open system interconnection (OSI) Model

Conceptual frame work used to understand network interactions in seven layers. The OSI Model standardizes the functions of a telecommunication or computing system into seven abstraction layers, facilitating communication over the network.

Layer 1

Physical Layer, responsible for transmitting raw data over physical media.

Equipment in the Physical layer.

Includes cables, switches, and network interface cards.

Physical layer data.

Raw binary data transmitted over physical medium.

Layer 2

Data Link Layer, responsible for node-to-node data transfer and error detection. It establishes, maintains, and terminates connections between two physically connected devices.

Data link layer.

Handles the framing of data packets.

Media access control (MAC)

manages protocol access in the to the physical network medium. Is responsible for addressing and channel access control mechanisms. Sub layer of layer 2.

Layer 3

Network layer. Responsible for the logical addressing and routing packets across different networks. Determines the best path for data transmission by using routing protocols. Manages packet forwarding.

Layer 3 devices.

Router

Layer 4.

Transport layer. providing reliable transparent transfer of data between end system. it ensures complete data transfer with mechanisms for error correction, flow control, and segmentation/ de-segmentation.

Layer 4 data.

TCP, UDP.

Layer 5 

Session layer. Manages the setup, maintenance, and termination of sessions. 

Layer 5 protocols.

Netbios, RCP

Layer 6.

Presentation layer. Translation, encryption and compression of data between the application and network frames. 

Layer 7.

Application layer. Serves as the interface between the user and the network services.

Physical appliances.

Dedicated hardware devices focused on specific network functions, offering high performance and reliability but a higher cost and with space requirements.

Virtual appliances.

Software based solutions that run on virtual machines, providing similar functionalities with greater flexibility, scalability and cost. But the raw performance might not be as good.

Router

Operates on the network layer. Directs data packets between different networks based on ip address. Provides network security features like firewalls and VPN support.

Routing tables

Routing tables are used by routers to determine the best path for forwarding packets.

Layer two switch.

Operates at the Data link layer forwarding data based on the MAC address. Creates separate collision domains for each port, improving network efficiency by reducing collisions. These are used to connect devices within the same network or VLAN.

Layer 3 capable switch

AKA multilayer switch, operates in layer 2 and 3. it can preform routing functions, forwarding data based on ip address, in addition to switching functions. This enables the switch to interconnect different subnets or VLANS within the same device.

Firewall

Network security device that monitors incoming and outgoing network traffic and decides whether to block or allow. Can be hardware based, software based, or a combinations of both.

IDS

passively monitors and alerts systems administrators of suspicious activity.

IPS

Actively blocks and prevents such activities based on detected anomalies and policy’s to protect the network from threats.

Load Balancer