networking

Dynamic Routing

Auto discovery, auto updates, best path, adapts to topology changes

Static Routing

Manual configuration, manual updates, small networks, default routes

what is Peer-to-Peer (P2P)

Devices communicate directly without central server

P2P Advantages

Easy setup, low cost, less complex, printer and file sharing

P2P Disadvantages

No centralized administration, less secure, poor scalability, poor performance

what is Fault Tolerance

Redundancy to reduce impact of failures

Fault Tolerance Characteristics

Redundant paths, packet switching, multiple routes

Scalability

Network growth without performance loss

Scalability Characteristics

More users/devices, maintains performance, standards-based

QoS

Prioritizes important traffic (voice/video)

QoS Characteristics

Traffic prioritization, low delay, low jitter, low packet loss

Security

Protects data and resources from unauthorized access

Confidentiality

Authorized access only

Integrity

Data not modified or tampered with

Availability

Systems accessible when needed

SVI

Logical interface for switch management

VLAN 1 SVI Purpose

Remote switch management

VLAN 1 Step 1

interface vlan 1

VLAN 1 Step 2

ip address

VLAN 1 Step 3

no shutdown

OSI Model

7-layer networking model

Application Layer

User services and applications

Presentation Layer

Formatting, encryption, compression

Session Layer

Session management

Transport Layer

Segmentation, end-to-end communication

Network Layer

Routing, logical addressing

Data Link Layer

MAC addressing, frame transmission

Physical Layer

Bit transmission over media

TCP/IP Model

4-layer internet model

TCP/IP Application Layer

User services (OSI 5-7)

TCP/IP Transport Layer

TCP and UDP communication, segmentation

TCP/IP Internet Layer

IP routing, logical addressing

TCP/IP Network Access Layer

Hardware and media access

Network Layer Protocols

IP, ICMP

IP Characteristics

Logical addressing, ip routing, path selection

what does ICMP do

Error reporting, network diagnostics

TCP

Reliable, connection-oriented, acknowledgements

UDP

Fast, connectionless, no guaranteed delivery

Network Layer PDU

Packet

TCP Step 1

SYN

TCP Step 2

SYN-ACK

TCP Step 3

ACK

LLC Sublayer

Identifies upper-layer protocols, flow control

Communication Elements

Sender, receiver, message, medium

UTP

Unshielded twisted pair cable

UTP Characteristics

RJ-45, low cost, easy installation, twisted pairs

Attenuation

Signal weakening over distance

STP Advantage

Blocks EMI/RFI

Fiber Optic

Light-based data transmission

Fiber Advantages

High bandwidth, long distance, immune to EMI/RFI

Single-Mode Fiber

Small core, laser, long distance transmission

Multimode Fiber

Large core, LED, short distance transmission

Wireless Advantages

Mobility, flexibility, no cables

Wireless Limitations

Interference, limited range, security risks

Directly Connected Route

Auto-added when interface is active

Default Route

Used when no specific route exists

show ip route codes

L=Local, C=Connected, S=Static, O=OSPF, D=EIGRP

what is ARP

IP to MAC resolution

ARP Functions

IP-MAC mapping, ARP table maintenance

Layer 2 Address

MAC address

Layer 3 Address

IP address

ARP Process

Check table, broadcast, reply, store mapping

First Ping Fails

ARP table empty

Second Ping Works

MAC already learned

Ping Requirements

IPs, MACs, ARP, route

ARP Issues

Spoofing, poisoning, broadcast traffic

Switch MAC Learning

Learns source MAC into table

Store-and-Forward Switching

Full frame check before forwarding

Store-and-Forward Characteristics

Error check, CRC, full frame

show ip interface brief

IPv4 interface status

show ipv6 interface brief

IPv6 interface status

show ip route

IPv4 routing table

show ipv6 route

IPv6 routing table

show interfaces

Detailed interface stats

show running-config

Current configuration

ICMP Echo

Ping request/reply

ICMP Destination Unreachable

Destination cannot be reached

ICMP Time Exceeded

TTL expired

Ping Fail Reasons

Wrong IP, no route, firewall, interface down

Traceroute

Packet path hops

DHCP

Automatic IP configuration

DHCP Assigns

IP, subnet mask, gateway, DNS

DHCP Advantages

Automatic setup, no conflicts, less manual work

DHCP DORA

Discover, Offer, Request, Acknowledge

Hardware Threats

Device/cable damage

Environmental Threats

Heat, humidity, cold

Electrical Threats

Power issues, surges, loss

Maintenance Threats

electrostatic discharge, poor cabling, labeling issues

Technological Vulnerabilities

OS/TCP-IP/equipment weaknesses

Configuration Vulnerabilities

Weak passwords, default settings, misconfig

Security Policy Vulnerabilities

No policy, weak access control

Device Hardening

Passwords, disable services, patches

Strong Passwords

8-10+ chars, mixed case, numbers, symbols

Password Encryption

encrypts password in configuration

Min Password Length

Sets minimum password length

Login Block

Blocks after failed attempts

Exec Timeout

Logs out idle sessions

SSH

Encrypted remote remote access

Telnet

Unencrypted remote access

SSH Setup

Hostname, domain, RSA keys, user, ssh only