Cisco Networking Study Guide Overview

RFID Tags

These use radio waves to automatically identify and track tags attached to objects.

Throughput

This is the actual amount of data that successfully transfers across a network in a given time.

Bandwidth

This is the theoretical maximum capacity of a network connection - the potential speed.

Host

Any device connected to a network that can send or receive data.

Client

A type of host that requests services or information from a server.

Server

A type of host that provides services or information to clients.

End Device (Host)

This is the source or destination of a message on a network.

Cable Television (Coaxial Cable)

This type of cable uses a central copper core surrounded by insulation and a braided shield to transmit TV signals.

DSL (Digital Subscriber Line)

A technology that uses existing phone lines to provide high-bandwidth internet access.

Peer-to-Peer Networks

A simple network where two or more computers can communicate directly with each other and share resources without a central server.

Wi-Fi

A popular wireless networking technology that uses radio waves to connect devices to local networks and the internet.

SSID (Service Set Identifier)

This is the name you see when you're choosing a Wi-Fi network to connect to.

Connecting to Wi-Fi (Android & iOS)

The steps involve finding the Wi-Fi settings, selecting the network name (SSID), choosing the security type (if any), and entering the password.

Tethering

Using your mobile device to share its internet connection with another device, either via Wi-Fi or a USB cable.

Ethernet (LAN - Local Area Network)

A common technology for wired networks within a limited geographical area (like your home).

Category 5e Cable

A common type of twisted-pair copper cable used for Ethernet networks.

Coaxial Cable

Used for TV and sometimes internet. It has better shielding than some other copper cables.

Fiber-Optic Cable

Uses thin strands of glass or plastic to transmit data as pulses of light.

Timing

The speed at which data bits are transmitted across the network.

Encapsulation

The process of adding headers (and sometimes trailers) to data as it moves down the layers of the TCP/IP or OSI model.

RFCs (Request For Comments)

These are technical documents that serve as the internet standards.

TCP/IP Model

A four-layer model that describes how data is transmitted over the internet.

Application

Interacts with user applications and includes encoding of data. (e.g., HTTP, DNS)

Transport

Provides reliable (TCP) or unreliable (UDP) end-to-end communication between devices.

Internet

Handles addressing and routing of data packets across networks (IP).

Network Access

Controls the physical hardware and media used for the network connection.

OSI Model

A seven-layer conceptual model for network communication.

Physical

Deals with the physical transmission of bits over a medium (cables, wireless).

Data Link

Handles the exchange of data frames between devices on the same local network.

Network

Responsible for routing data packets across networks (IP).

Transport

Provides segmentation, transfer, and reassembly of data.

Session

Manages and controls connections between applications.

Presentation

Handles data formatting, encryption, and compression.

Application

Provides network services to end-user applications.

Standard

A set of rules that define how a network operates, ensuring compatibility between different devices and manufacturers.

Protocol

A specific set of rules governing a particular type of communication that occurs over a network (e.g., HTTP for web browsing).

Network Media Types

The physical means by which data is transmitted.

Metal wires (cables)

Data is transmitted as electrical impulses.

Glass/plastic fibers (fiber-optic)

Data is transmitted as pulses of light.

Wireless transmission

Data is transmitted as electromagnetic waves.

IPv4 Address

A 32-bit numerical address assigned to each device (host) on a network for identification and communication.

Dotted-Decimal Notation

The format used to write IPv4 addresses, with four 8-bit numbers (octets) separated by dots.

Network Portion

The part of the IP address that identifies the network the host belongs to.

Host Portion

The part of the IP address that identifies the specific device within that network.

Subnet Mask

A 32-bit number that separates the network and host portions of an IP address (e.g., 255.255.255.0).

Routers

Network devices that use the network portion of an IP address to forward data packets to the correct network.

Unicast Transmission

Sending a message directly from one specific device to another specific device using its unique IP address.

Broadcast Transmission

Sending a message to all devices on a local network.

Multicast Transmission

Sending a message to a specific group of devices that have joined a multicast group.

Public IPv4 Addresses

Unique IP addresses used on the internet. These are routable globally.

Private IPv4 Addresses

IP addresses used within a local network. These are not routable on the internet.

NAT (Network Address Translation)

A process used by routers to translate private IP addresses on a local network to a single public IP address when communicating with the internet.

Loopback Addresses (127.x.x.x)

Used by a device to send network traffic back to itself for testing purposes.

Link-Local Addresses (169.254.x.x)

Automatically assigned to a device when it cannot obtain an IP address from a DHCP server.

IPv4 Address Classes (A, B, C, D, E)

Older method of categorizing IP addresses based on network size. Class A for large, B for medium, C for small. D for multicast, E for experimental.

ARP (Address Resolution Protocol)

A protocol used in Ethernet LANs to find the MAC address associated with a known IP address on the same network segment.

Subnetting

Dividing a larger network into smaller subnetworks to improve performance, reduce broadcast traffic, and enhance security.

Static IP Assignment

Manually configuring the IP address, subnet mask, and default gateway on each host.

DHCP (Dynamic Host Configuration Protocol)

A protocol that automatically assigns IP addresses and other network configuration information to hosts on a network.

DHCP Server

A network device (often a router) that runs the DHCP service and manages a pool of available IP addresses.

DHCP Lease

The period of time for which an IP address is assigned to a host by a DHCP server.

DHCP Discover

The initial broadcast message sent by a client trying to find a DHCP server.

DHCP Offer

The response from a DHCP server offering an available IP address to the client.

DHCP Request

The message sent by the client accepting the offered IP address.

DHCP Acknowledgment

The final message from the DHCP server confirming the IP address assignment.

Default Gateway

The IP address of the router on your local network that your device sends traffic to when it needs to communicate with devices on other networks (including the internet).

ISP (Internet Service Provider)

The company that provides you with internet access. Your router connects to the ISP.

DHCP Client (Router to ISP)

Your router acts as a DHCP client when it obtains a public IP address from your ISP.

NAT

Enables multiple devices on your private network to share the single public IP address assigned to your router by the ISP.

ARP Request (Broadcast)

When a host knows the IP address of another device on the same local network but needs its MAC address, it sends a broadcast message asking, 'Who has this IP address? Tell me your MAC address.'

Response (Unicast)

The device with the matching IP address replies directly to the requesting host with its MAC address.

ARP Table

A table stored on each host that maps IP addresses to MAC addresses of devices on the same local network.

Broadcast Domain

The area of a network where broadcast messages are forwarded. Routers typically limit broadcast domains.

Distribution Layer

A layer in a larger network that connects multiple access layer networks (local networks) and controls traffic between them.

Forwarding Decisions (Routers)

Routers examine the destination IP address of a packet and consult their routing tables to determine the best path to forward the packet.

Routing Table

A table stored on a router that contains information about different networks and the best way to reach them.

Directly Connected Networks

Networks that a router has a direct interface to.

Next Hop Router

If the destination network is not directly connected, the router forwards the packet to another router (the next hop) that is closer to the destination.

Dynamic Routing

Routing tables can be updated automatically by routing protocols that allow routers to share information about network paths.

Static Routing

Routing tables can be configured manually by a network administrator.

Latency

The delay in the transfer of data across a network.

UDP (User Datagram Protocol)

A connectionless, unreliable transport protocol. It sends data quickly without establishing a connection or guaranteeing delivery.

TCP (Transmission Control Protocol)

A connection-oriented, reliable transport protocol. It establishes a connection before sending data, ensures ordered delivery, and retransmits lost packets.

Port Numbers

Logical numbers used by TCP and UDP to identify specific applications or services running on a host.

Well-Known Ports (1-1023)

Standard ports assigned to common network services (e.g., HTTP: 80, FTP: 21, DNS: 53).

Registered Ports (1024-49151)

Ports registered by software vendors for specific applications.

Private/Dynamic Ports (49152-65535)

Ports used temporarily by client applications for communication with servers.

Source Port

A dynamically assigned port number used by the client to identify its side of a communication.

Netstat Command

A command-line tool used to display active network connections, listening ports, Ethernet statistics, the IP routing table, IPv4 statistics (for IP, ICMP, TCP, and UDP protocols), IPv6 statistics (for IPv6, ICMPv6, TCP over IPv6, and UDP over IPv6 protocols), and network interface statistics.

Server (Application Layer)

A software application running on a host that provides information or services to clients (e.g., a web server).

Client (Application Layer)

A software application that requests services from a server (e.g., a web browser).

URI (Uniform Resource Identifier)

A generic term for all types of names and addresses that refer to objects on the World Wide Web.

URL (Uniform Resource Locator)

A type of URI that specifies where an identified resource is available and the mechanism for retrieving it.

URN (Uniform Resource Name)

A type of URI that provides a persistent, location-independent name for a resource (less commonly used in everyday browsing).

DNS (Domain Name System)

A hierarchical and distributed naming system for computers, services, or any resource connected to the internet or a private network. It translates human-readable domain names (like google.com) into IP addresses.

HTTP (HyperText Transfer Protocol)

The foundation of data communication for the World Wide Web. It defines how messages are formatted and transmitted between web browsers and web servers.