Main

Network layer- Layer 3

IP addressing / Routing
PDU/Protocol Data Unit - Packets, Segment of data.
examine components of the Network layer of the OSI model. These components include the IP address, subnet mask, and default gateway for a device. Configuration details of the IPv4 and IPv6 protocols are a part of the Network layer.
IP addresses are logical addresses mapped to a physical component
Routers work at this level - Sometimes called layer 3 switch - Moves data across networks
Responsible for routing and IP addressing
Multi-layer switches operate at Data-link layer 2 and Network layer 3 layers

Protocols - currenty most protocols that start with I operate at level 3 (Except for IMAP)- ICMP, IGRP, IGMP, IPSec
If involving IP addressing it will typically be network

IP - Internet Protocol - IPv4 IPv6
Provides logical network and host addressing
Most routers today use IP for routing data through the network
IPConfig for Windows / IFConfig for linux

ICMP - Internet Control Messaging Protocol
Responsible for echoing utillities like Ping, Tracert, traceroute
Ping is used to test basic physical connectivity for local and remote hosts
If a ping fails perhaps use Tracert / Traceroute to see the hops to diagnose the problem
where the ping fails
Tracert for Windows, Traceroute for Linux - Chases hops through routers
Ping a local computer on my network - If I can reach it, great!
Then I'll ping a remorte computer - One on the other side of the router / If I can't raeach that remote host I'll use Tracert/Traceroute so I can see the message leave from me
Goes to Router 1, Goes to Router 2, Then It doesn't look like it will pass router 3