Mark A. Dyewas the technology manager and training manager for the Bevill Center at Gadsden State Community
College, where he also managed and taught in the Cisco Academy program. He now works full time as an assessment
and curriculum developer with Cisco. Mark also has maintained a private information technology consulting business
since 1985. Mark�s 30+-year career has included roles as biomedical instrumentation technician, field service engineer,
customer service supervisor, network engineer, and instructor.
Rick McDonald teaches computer and networking courses at the University of Alaska Southeast in Ketchikan, Alaska.
He is developing methods for delivering hands-on training via distance in Alaska using web-conferencing and NETLAB
tools. Rick worked in the airline industry for several years before returning to full-time teaching. He taught
CCNA and CCNP courses in the Cisco Networking Academy in North Carolina and was a CCNA instructor trainer.
Antoon �Tony�W. Rufi currently is the associate dean of computer and information science for all the ECPI College
of Technology campuses. He also teaches the Cisco Networking Academy CCNA, CCNP, Network Security, Fundamentals
of Wireless LAN, and IP Telephony curricula. Before becoming an instructor for ECPI, he spent almost 30 years in
the United States Air Force, working on numerous electronic projects and computer programs.
Summary
Network Fundamentals, CCNA Exploration Companion Guide is the official supplemental textbook for the Network
Fundamentals course in the Cisco Networking Academy CCNA Exploration curriculum version 4. The course, the first
of four in the new curriculum, is based on a top-down approach to networking. The Companion Guide, written and
edited by Networking Academy instructors, is designed as a portable desk reference to use anytime, any where. The
book's features reinforce the material in the course to help you focus on important concepts and organize your
study time for exams.
Table of Contents
Table of Contents
Introduction
Chapter 1 Living in a Network-Centric World
Objectives
Key Terms
Communicating in a Network-Centric World
Networks Supporting the Way We Live
Examples of Today�s Popular Communication Tools
Networks Supporting the Way We Learn
Networks Supporting the Way We Work
Networks Supporting the Way We Play
Communication: An Essential Part of Our Lives
What Is Communication?
Quality of Communication
The Network as a Platform
Communicating over Networks
Elements of a Network
Converged Networks
The Architecture of the Internet
The Network Architecture
Fault-Tolerant Network Architecture
Scalable Network Architecture
Providing Quality of Service
Providing Network Security
Trends in Networking
Where Is It All Going?
Networking Career Opportunities
Summary
Activities and Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Chapter 2 Communicating over the Network
Objectives
Key Terms
The Platform for Communications
The Elements of Communication
Communicating the Messages
Components of the Network
End Devices and Their Role on the Network
Intermediary Devices and Their Role on the Network
Network Media
LANs, WANs, and Internetworks
Local-Area Networks
Wide-Area Networks
The Internet: A Network of Networks
Network Representations
Protocols
Rules That Govern Communications
Network Protocols
Protocol Suites and Industry Standards
Interaction of Protocols
Technology-Independent Protocols
Using Layered Models
The Benefits of a Layered Model
Protocol and Reference Models
TCP/IP Model
Communication Process
Protocol Data Units and Encapsulation
Sending and Receiving Process
OSI Model
Comparing the OSI Model to the TCP/IP Model
Network Addressing
Addressing in the Network
Getting Data to the End Device
Getting Data Through the Internetwork
Getting Data to the Right Application
Summary
Activities and Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Chapter 3 Application Layer Functionality and Protocols
Objectives
Key Terms
Applications: The Interface Between the Networks
OSI and TCP/IP Model
Application Layer Software
User Applications, Services, and Application Layer Protocols
Application Layer Protocol Functions
Making Provisions for Applications and Services
Client/Server Model
Servers
Application Layer Services and Protocols
Peer-to-Peer (P2P) Networking and Applications
Application Layer Protocols and Services Examples
DNS Services and Protocol
WWW Service and HTTP
E-Mail Services and SMTP/POP Protocols
E-Mail Server Processes: MTA and MDA
FTP
DHCP
File-Sharing Services and SMB Protocol
P2P Services and Gnutella Protocol
Telnet Services and Protocol
Summary
Activities and Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Chapter 4 OSI Transport Layer
Objectives
Key Terms
Roles of the Transport Layer
Purpose of the Transport Layer
Supporting Reliable Communication
TCP and UDP
Port Addressing
Segmentation and Reassembly: Divide and Conquer
TCP: Communicating with Reliability
Making Conversations Reliable
TCP Server Processes
TCP Connection Establishment and Termination
TCP Three-Way Handshake
TCP Session Termination
TCP Acknowledgment with Windowing
TCP Retransmission
TCP Congestion Control: Minimizing Segment Loss
UDP: Communicating with Low Overhead
UDP: Low Overhead Versus Reliability
UDP Datagram Reassembly
UDP Server Processes and Requests
UDP Client Processes
Summary
Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Chapter 5 OSI Network Layer
Objectives
Key Terms
IPv4
Network Layer: Communication from Host to Host
IPv4: Example Network Layer Protocol
IPv4 Packet: Packaging the Transport Layer PDU
IPv4 Packet Header
Networks: Dividing Hosts into Groups
Creating Common Groups
Why Separate Hosts into Networks?
Dividing Networks from Networks
Routing: How Data Packets Are Handled
Device Parameters: Supporting Communication Outside the Network
IP Packets: Carrying Data End to End
Gateway: The Way Out of the Network
Route: A Path to a Network
Destination Network
Next Hop: Where the Packet Goes Next
Packet Forwarding: Moving the Packet Toward Its Destination
Routing Processes: How Routes Are Learned
Static Routing
Dynamic Routing
Routing Protocols
Summary
Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Chapter 6 Addressing the Network: IPv4
Objectives
Key Terms
IPv4 Addresses
Anatomy of an IPv4 Address
Binary-to-Decimal Conversion
Decimal-to-Binary Conversions
Addressing Types of Communication: Unicast, Broadcast, Multicast
IPv4 Addresses for Different Purposes
Types of Addresses in an IPv4 Network Range
Subnet Mask: Defining the Network and Host Portions of the Address
Public and Private Addresses
Special Unicast IPv4 Addresses
Legacy IPv4 Addressing
Assigning Addresses
Planning to Address the Network
Static or Dynamic Addressing for End-User Devices
Selecting Device Addresses
Internet Assigned Numbers Authority (IANA)
ISPs
Calculating Addresses
Is the Host on My Network?
Calculating Network, Hosts, and Broadcast Addresses
Basic Subnetting
Subnetting: Dividing Networks into Right Sizes
Subnetting a Subnet
Testing the Network Layer
Ping 127.0.0.1: Testing the Local Stack
Ping Gateway: Testing Connectivity to the Local LAN
Ping Remote Host: Testing Connectivity to Remote LAN
Traceroute (tracert): Testing the Path
ICMPv4: The Protocol Supporting Testing and Messaging
Overview of IPv6
Summary
Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Chapter 7 OSI Data Link Layer
Objectives
Key Terms
Data Link Layer: Accessing the Media
Supporting and Connecting to Upper-Layer Services
Controlling Transfer Across Local Media
Creating a Frame
Connecting Upper-Layer Services to the Media
Standards
MAC Techniques: Placing Data on the Media
MAC for Shared Media
MAC for Nonshared Media
Logical Topology Versus Physical Topology
MAC: Addressing and Framing Data
Data Link Layer Protocols: The Frame
Framing: Role of the Header
Addressing: Where the Frame Goes
Framing: Role of the Trailer
Sample Data Link Layer Frames
Putting It All Together: Following Data Through an Internetwork
Summary
Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Chapter 8 OSI Physical Layer
Objectives
Key Terms
Physical Layer: Communication Signals
Purpose of the Physical Layer
Physical Layer Operation
Physical Layer Standards
Physical Layer Fundamental Principles
Physical Signaling and Encoding: Representing Bits
Signaling Bits for the Media
Encoding: Grouping Bits
Data-Carrying Capacity
Physical Media: Connecting Communication
Types of Physical Media
Copper Media
Media Connectors
Summary
Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Chapter 9 Ethernet
Objectives
Key Terms
Overview of Ethernet
Ethernet: Standards and Implementation
Ethernet: Layer 1 and Layer 2
Logical Link Control: Connecting to the Upper Layers
MAC: Getting Data to the Media
Physical Implementations of Ethernet
Ethernet: Communication Through the LAN
Historic Ethernet
Legacy Ethernet
Current Ethernet
Moving to 1 Gbps and Beyond
Ethernet Frame
Frame: Encapsulating the Packet
Ethernet MAC Address
Hexadecimal Numbering and Addressing
Another Layer of Addressing
Ethernet Unicast, Multicast, and Broadcast
Ethernet MAC
MAC in Ethernet
CSMA/CD: The Process
Ethernet Timing
Interframe Spacing and Backoff
Ethernet Physical Layer
10- and 100-Mbps Ethernet
1000-Mbps Ethernet
Ethernet: Future Options
Hubs and Switches
Legacy Ethernet: Using Hubs
Ethernet: Using Switches
Switches: Selective Forwarding
Address Resolution Protocol (ARP)
Resolving IPv4 Addresses to MAC Addresses
Maintaining a Cache of Mappings
ARP Broadcast Issues
Summary
Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Chapter 10 Planning and Cabling Networks
Objectives
Key Terms
LANs: Making the Physical Connection
Choosing the Appropriate LAN Device
Device Selection Factors
Device Interconnections
LAN and WAN: Getting Connected
Making LAN Connections
Making WAN Connections
Developing an Addressing Scheme
How Many Hosts in the Network?
How Many Networks?
Designing the Address Standard for Your Internetwork
Calculating the Subnets
Calculating Addresses: Case 1
Calculating Addresses: Case 2
Device Interconnections
Device Interfaces
Making the Device Management Connection
Summary
Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Chapter 11 Configuring and Testing Your Network
Objectives
Key Terms
Configuring Cisco Devices: IOS Basics
Cisco IOS
Access Methods
Configuration Files
Introducing Cisco IOS Modes
Basic IOS Command Structure
Using CLI Help
IOS Examination Commands
IOS Configuration Modes
Applying a Basic Configuration Using Cisco IOS
Naming Devices
Limiting Device Access: Configuring Passwords and Banners
Managing Configuration Files
Configuring Interfaces
Verifying Connectivity
Test the Stack
Testing the Interface
Testing the Local Network
Testing Gateway and Remote Connectivity
Tracing and Interpreting Trace Results
Monitoring and Documenting Networks
Basic Network Baselines
Capturing and Interpreting Trace Information
Learning About the Nodes on the Network
Summary
Labs
Check Your Understanding
Challenge Questions and Activities
To Learn More
Appendix Check Your Understanding and Challenge Questions Answer Key
