Comptia Network+ Exam 2

Checksum

Error detection method used to verify data integrity (no correction)

Flow Control

Prevents sender from overwhelming receiver

Multiplexing

Allows multiple applications to share a single connection using ports

Sequence Number

Used to keep packets in order and detect missing data

Windowing

Controls how much data can be sent before receiving an ACK

TCP Flags

URG, ACK, PSH, RST, SYN, FIN

SYN Flag

Initiates a TCP connection

ACK Flag

Acknowledges received data

FIN Flag

Closes a TCP connection

RST Flag

Resets a connection

PSH Flag

Pushes data immediately to application

URG Flag

Indicates urgent data

TCP 3-Way Handshake

SYN → SYN-ACK → ACK

TCP Connection Close

FIN → ACK → FIN → ACK

TCP Socket

Combination of IP address and port number

TCP

Reliable, connection-oriented protocol using acknowledgements

UDP

Unreliable, connectionless protocol with no acknowledgements

TCP vs UDP Reliability

TCP uses ACKs, UDP does not

TCP vs UDP Connection

TCP is connection-oriented, UDP is connectionless

TCP vs UDP Error Handling

TCP detects and corrects errors, UDP only detects

TCP vs UDP Speed

TCP is slower, UDP is faster

Router

Device that forwards packets between networks

ICMP

Protocol used for diagnostics like ping and traceroute

Ping

Tests connectivity using ICMP

Traceroute

Shows path packets take through network

Static IP

Manually assigned IP address

Dynamic IP

Automatically assigned IP via DHCP

DHCP

Dynamic Host Configuration Protocol assigns IP addresses automatically

DHCP Ports

67 (server), 68 (client)

DORA Process

Discover, Offer, Request, Acknowledge

ipconfig /all

Command to view full network configuration including DHCP info

IPv4

32-bit addressing using decimal format

IPv6

128-bit addressing using hexadecimal format

Class A IP Range

1–126

Class B IP Range

128–191

Class C IP Range

192–223

Private Class A

10.0.0.0 – 10.255.255.255

Private Class B

172.16.0.0 – 172.31.255.255

Private Class C

192.168.0.0 – 192.168.255.255

Loopback Address

127.0.0.1 used to test local machine

APIPA

169.254.x.x assigned when DHCP fails

Network Bits

Represented by 1s in subnet mask

Host Bits

Represented by 0s in subnet mask

Subnet Mask

Defines network vs host portion of IP

Slash Notation

/CIDR notation representing subnet mask (e.g., /24)

Unicast

One-to-one communication

Broadcast

One-to-all communication

Multicast

One-to-many group communication

Subnetting

Process of dividing a network into smaller subnetworks

Routing Table

Stores best paths for packet forwarding

Topology Table

Stores all known routes in network

Interior Routing Protocols

RIP, OSPF, EIGRP

Exterior Routing Protocol

BGP

Distance Vector Routing

Uses hop count and shares full routing table with neighbors

Classful Routing

RIP v1 does not include subnet information

Classless Routing

RIP v2 includes subnet information

IPv6 Routing Protocols

OSPFv3, EIGRP, BGP

Convergence

Time it takes for network to update after a change

Fast Convergence Protocols

OSPF and EIGRP

ipconfig

Displays IP configuration

ping

Tests network connectivity

tracert

Shows packet path to destination

nslookup

Queries DNS records

ipconfig /all

Shows detailed network info

ipconfig /release

Releases current IP address

ipconfig /renew

Renews IP address

ping -t

Pings continuously

ping -n

Specifies number of echo requests

HTTP

Port 80

HTTPS

Port 443

FTP

Port 21

SSH

Port 22

Telnet

Port 23

SMTP

Port 25

DNS

Port 53

DHCP

Ports 67/68

POP3

Port 110