GROUP 2: NETWORK OPERATING SYSTEMS & CONFIGURATION

NETWORK OPERATING SYSTEM (NOS)

is specialized software that manages and coordinates network resources, services, and communication among multiple computers and devices in a network. It manages hardware resources and provides services such as routing, switching, and security.

OPERATING SYSTEM COMPONENTS (OS Shell)

its either a command-line interface (CLI) or a graphical user interface (GUI) and enables a user to interface with applications.

OPERATING SYSTEM COMPONENTS (OS Kernel)

it communicates directly with the hardware and manages how hardware resources are used to meet software requirements

OPERATING SYSTEM COMPONENTS (Hardware)

The physical part of a computer including underlying electronics.

CISCO IOS (INTERNETWORK OPERATING SYSTEM)

the proprietary operating system developed by Cisco Systems for its networking devices such as routers, switches, and firewalls. It provides the command-line interface (CLI) and networking capabilities needed to configure, operate, and troubleshoot Cisco hardware.

FUNCTIONS OF CISCO IOS

• Routing - Determines the best path for data packets across networks (e.g., OSPF, EIGRP)

• Switching - Controls data forwarding within a LAN (e.g., VLANs, STP)

• Security - Provides features like Access Control Lists (ACLs), VPNs, and firewalls

• QoS (Quality of Service) - Manages traffic prioritization and bandwidth allocation • Network Management - Supports SNMP, syslog, NetFlow, and remote management

CISCO IOS MODES (USER EXEC MODE (Router>))

• This is where you start when you connect.

• You can only do basic things, like look at a directory or ask what time it is.

• You cannot change anything.

• Prompt: Router>

CISCO IOS MODES (PRIVILEGED EXEC MODE (Router#))

• From the lobby, you use the enable command to enter the secure security office.

• Here, you have master keys. You can see everything, run advanced diagnostics, and reboot the system.

• You still can't configure the network, but you can see all the settings and enter the areas where you can make changes.

• Prompt: Router#

CISCO IOS MODES (GLOBAL CONFIGURATION MODE (Router(config)#))

• From the security office, you use configure terminal to enter the architect's office.

• Now you can make changes that affect the entire building (the whole device), like setting the device's name or password.

• Prompt: Router(config)#

CISCO IOS MODES (INTERFACE CONFIGURATION MODE (Router(config-if)#))

• While in the architect's office, you "walk over" to a specific door (like an Ethernet port) to configure it.

• Here, you can set the speed of that port, give it an IP address, or turn it on/off.

• Prompt: Router(config-if)#

CISCO IOS MODES (LINE CONFIGURATION MODE (Router(config-line)#))

• While in the architect's office, you "pick up" a specific communication line (like the console or SSH port).

• Here, you set the rules for how people can log in, like setting a password for the console.

• Prompt: Router(config-line)#

CISCO IOS BOOT PROCESS - POST (Power-On Self-Test)

Tests and verifies whether the router's hardware components (CPU, memory, interfaces) are working properly.

CISCO IOS BOOT PROCESS - Load Bootstrap Program

A small program stored in ROM that initializes the hardware and locates the IOS image to load.

CISCO IOS BOOT PROCESS - Find and Load Cisco IOS Image

Locate and load the IOS image into RAM

CISCO IOS BOOT PROCESS - Locate and Load Startup Configuration File

Load the device's saved configuration.

CISCO IOS BOOT PROCESS - Running Configuration

The active configuration controlling the router or switch.

CISCO IOS BOOT PROCESS - ROMMON Mode (Fallback)

Recovery mode used when IOS image is missing or corrupted.

HOSTNAMES

a unique, human-readable label for a device (for example, R1-HQ-Main). It helps you and your team distinguish between devices in logs, CLI prompts, and network maps.

BANNER MESSAGES

Banners are messages that are displayed when someone attempts to gain access to a device. Banners are an important part of the legal process in the event that someone is prosecuted for breaking into a device

IP ADDRESS

a set of characters that are unique to a specific device. It is what allows a device that is connected in a network to be located.

IPv4

• Introduced in 1981 and became the standard address system • Uses a 32-bit dotted decimal notation, split into 4 sections valuing a number from 0 to 255 • Example: 192.168.1.1 • Limited to 4.3 billion unique IP addresses

IPv6

• Introduced in 2012 to address the growing amount of computers and devices • Uses an alphanumeric hexadecimal notation, split into 8 sections, valuing from 0 to FFFF • Example: 2001:db8::1 • Supports 340 undecillion unique IP addresses

SUBNET MASK

iTs a 32-bit number that is used to logically divide an IP address into two main parts

Network Portion

Identifies the specific network or subnetwork a device belongs to

Host Portion

Identifies the specific device within that network.

DEFAULT GATEWAY

the IP address of the router interface that is connected to the local network. Its main purpose is to serve as the exit point for all data traffic that is destined for a device on a different network.

Static IP Addressing

• Manual setup by an admin.

• Permanent address that doesn't change.

• Used for: Servers, printers, websites (needs a stable address).

Dynamic IP Addressing:

• Automatic assignment from a DHCP server.

• Temporary address that can change.

• Used for: Laptops, phones, most user devices.

STATIC PRO’S

Stable, reliable for hosting services.

STATIC CON’S

Manual work, less secure, more expensive.

DYNAMIC PROS

Pros: Cheaper and easier to set up, automatic configuration, more secure

DYNAMIC CONS

Not ideal for hosting, may cause occasional connection drops