CISCO Exam 1

Define Internet

The Internet is a global mesh of interconnected computer networks that communicates using the standardized Internet Protocol Suite (TCP/IP) to link billions of devices worldwide. It is a "network of networks" consisting of private, public, academic, business, and government networks.

Who owns the Internet?

No single person, company, or government owns the Internet

How do we ensure effective communication across the Internet?

We ensure effective communication by adhering to standardized network protocols (such as TCP/IP). These rules govern how data is formatted, addressed, transmitted, routed, and received, ensuring that diverse hardware and software platforms can seamlessly interact.

How large/small can a network be?

As small as a Personal Area Network connecting a single user's devices via Bluetooth to as large as the Internet

Client

A computer or software application that requests services, data, or resources from a server.

Server

A computer or system that provides resources, data, services, or programs to other computers (clients) over a network.

Host

Any device connected to a network that has a unique IP address and can send or receive traffic.

Peer-to-Peer Network

A decentralized network architecture where every computer (peer) can act as both a client and a server, sharing resources directly without a centralized server.

Medium

The physical channel, pathway, or material (copper, fiber-optic, or wireless signals) used to transmit data signals between devices.

Topology Diagram

A visual map or schematic that illustrates the structure and layout of a network's connections and devices.

NIC (Network Interface Card)

The hardware component (circuit board or chip) that physically connects a device to a network medium.

Physical Port

A specialized physical receptacle on a networking device where a cable or connector plugs in.

Interface

A specialized port on a networking device (like a router) that connects to an individual network and often possesses specific IP configuration properties.

Convergence

The integration of data, voice, and video traffic over a single, shared network infrastructure using a unified set of protocols.

Network Architecture

The structural design and framework of a communication network, including its physical configuration, functional organization, and operational protocols.

Network Bandwidth

The maximum capacity of a network link to transmit data over a specific period, typically measured in bits per second (bps).

Cloud Computing

The on-demand delivery of computing services (servers, storage, databases, networking, software) over the Internet on a pay-as-you-go basis.

Data Center

A dedicated physical facility used by organizations to house their critical applications, data, and enterprise-grade computing hardware.

Powerline Networking

A technology that utilizes existing residential electrical wiring to transmit network data signals between rooms without running dedicated Ethernet cables.

What is the benefit of convergence

The primary benefit of convergence is cost efficiency and simplified management.

List some tasks performed by intermediary devices

Regenerating, Maintaining information, Notifying, Directing data, Classifying, Permitting or denying traffic

Give examples of end devices and intermediary devices

• End Devices: PC, Laptop, Smartphone, IP Phone, Network Printer, Smart TV.

• Intermediary Devices: LAN Switch, Router, Multilayer Switch, Wireless Access Point (WAP), Firewall.

List the 3 general types of network media

Copper, Fiber, Wireless

Know the criteria for choosing a type of network media

The maximum distance the media can successfully carry a signal

The environment in which the media is to be installed (e.g., electromagnetic interference)

The amount of data and the speed at which it must be transmitted (Bandwidth).

The cost of the media, connectors, and installation.

Differentiate between an intranet and an extranet

Intranet: Exclusive internal employees only

Extranet: Authorized external partners, suppliers, or clients

List and explain the four basic characteristics of network architecture

Fault Tolerance: The network can limit the impact of a failure by using redundant paths so communication continues seamlessly if a link drops.

Scalability: The network can expand quickly to support new users and applications without degrading the performance of existing users

Quality of Service (QoS): The network can prioritize specific types of traffic (like live video or voice calls) over less time-sensitive data (like email) to prevent lag

Security: Protects network assets and transmitted data from unauthorized access, modification, or theft

Give advantages of both circuit-switched and packet-switched networks

Circuit-Switched (Advantage): Provides a dedicated, constant path with guaranteed bandwidth and zero delay variation (ideal for traditional telephone calls)

Packet-Switched (Advantage): Highly efficient use of bandwidth because multiple users can share the same communication paths simultaneously; resilient if paths go down

List and define the 4 primary types of clouds

Public Cloud: Cloud services offered over the public internet to anyone who wants to purchase them

Private Cloud: Cloud infrastructure operated solely for a single organization, hosted either internally or externally

Hybrid Cloud: A composition of two or more clouds (private and public) that remain unique entities but are bound together

Community Cloud: Cloud infrastructure shared by several organizations with common concerns (e.g., compliance, security requirements)

Do companies typically build their own data centers or do they use commercial data centers?

Most small-to-medium companies use commercial data centers or cloud providers due to the immense cost of construction, maintenance, and power infrastructure.

Identify some of the most common external security threats to networks

Viruses, worms, and Trojan horses

Spyware and adware

Zero-day attacks (attacks occurring on the first day a vulnerability is known)

Threat actor attacks (hacker intrusions)

Denial of Service (DoS) attacks

Data interception and theft

List methods used to connect homes/businesses to the Internet

Home Connections: DSL (Digital Subscriber Line), Cable (Coaxial), Fiber-to-the-Home (FTTH), Cellular (4G/5G), Satellite

Business Connections: Dedicated Leased Lines (T1/E1, T3/E3), Business DSL, Metro Ethernet, Satellite

RAM (Random Access Memory)

Volatile memory. It stores the running-config, routing tables, ARP tables, and packet buffers. Data is lost when power is turned off

NVRAM (Non-Volatile RAM)

Non-volatile memory. It stores the startup-config. Data is saved when the device reboots

Flash Memory

Non-volatile memory. It stores the Cisco IOS operating system image file

ROM (Read-Only Memory)

Non-volatile memory. It stores the bootstrap code used to boot the router or switch

Startup-config vs. Running-config

The running-config is currently executing in active RAM, meaning any changes happen immediately but disappear on reboot. The startup-config is the backup configuration saved in NVRAM that loads when the device boots up

CLI Access & Ports

Console Port: Used for out-of-band management. It provides physical, local access using a rollover cable, usually during initial configuration or when network access is down.

VTY Lines (Telnet/SSH): Used for in-band management. It allows remote access across a local network or the internet.

Auxiliary (AUX) Port: Used for remote out-of-band management over a dial-up telephone modem (rarely used today).

Mode Hierarchy & Identification

User EXEC Mode: Prompts with Router>. It allows basic monitoring and limited view-only commands.

Privileged EXEC Mode (Enable Mode): Prompts with Router#. It allows full viewing of configurations, debugging, and file management.

Global Configuration Mode: Prompts with Router(config)#. It allows changes that affect the entire device.

Specific Configuration Submodes: Prompts like Router(config-if)# (Interface mode) or Router(config-line)# (Line mode). They change specific components.

What is DHCP

DHCP (Dynamic Host Configuration Protocol) is a network protocol used to automatically assign IP addresses, subnet masks, default gateways, and DNS server settings to client devices when they connect to a network

Is CISCO case sensitive?

No CISCO is not case sensitive

What are the 3 elements common to all communication methods

Sender, Receiver, Channel/medium

What is encoding

Converting information into a format suitable for transmission

What is decoding

Converting received information back into a form the destination can understand

What is encapsulation

Adding protocol information, such as headers, to data as it moves down through network layers

What is de-encapsulation

Removing protocol information as data moves up through network layers at the destination

Why are messages broken into segments before traveling across a network

Segmentation makes data easier to transmit, allows multiple users to share the network, and allows pieces of data to be managed independently

What is unicast

One sender → one receiver

What is multicast

One sender → a specific group of receivers

What is broadcast

One sender → all devices on the local broadcast domain/network

What is a protocol

A set of rules that determines how devices communicate

What is a protocol suite

A group of related protocols that work together to provide network communication

What is proprietary

Technology controlled by a particular company or organization rather than being an open standard.

What is an open standard

A publicly available standard that allows products from different manufacturers to work together

What is segmentation

Breaking a large message into smaller pieces for transmission

What is multiplexing

Combining multiple communications so they can share the same network connection

What are the 7 layers of the OSI model

Application, Presentation, Session, Transport, Network, Data Link, Physical

What are the 4 layers of the TCP/IP model

Application, Transport, Internet, Network Access

What is the PDU at the Application/Presentation/Session layers

Data

What is the PDU at the Transport layer

Segment for TCP; datagram for UDP

What is the PDU at the Network layer

Packet

What is the PDU at the Data Link layer

Frame

What is the PDU at the Physical layer

Bits

Why do we use layered models when studying networking

They break complicated networking processes into smaller, easier-to-understand sections and provide common standards for communication

What are advantages of segmentation

It makes data easier to manage, allows multiple conversations to share the network, improves efficiency, and can reduce the effect of errors

What is a disadvantage of segmentation

It creates additional overhead because each segment needs headers and the pieces may need to be reassembled

What is an IP address

A logical address used to identify a device/interface and its location on a network

What is a MAC address

A physical/data-link address used to identify a network interface on a local network

How many IP addresses are placed on a packet traveling over the Internet

Two: a source IP address and a destination IP address

How many MAC addresses are placed on a frame

Two: a source MAC address and a destination MAC address

Which addresses change as data travels through a remote network

MAC addresses change at each router hop. The source and destination IP addresses generally remain the same end-to-end, although NAT can modify IP addressing

What are the two parts of an IP address

The network portion and the host portion

What does ARP do

Address Resolution Protocol maps an IPv4 address to the corresponding MAC address on a local network

What is a proxy ARP

A router responds to an ARP request on behalf of another device, allowing the requesting device to communicate with a destination through the router