Menu
Coddy logo textTech
START LEARNING
flag En iconEnglishdown icon

Recap - Layer Three

Lesson 15 of 32 in Coddy's The OSI Model course.

challenge icon

Challenge

Easy

Layer 3 wrap-up. Print, in this order:

  1. The TTL a destination sees when a packet starts at 64 and crosses 5 routers
  2. The gateway letter for a packet to 10.1.9.9, using the routing table from the Routing Tables lesson (A = default, B = 10.0.0.0/8, C = 10.1.0.0/16)
  3. The protocol ping is built on (uppercase)

Expected output:

59
C
ICMP

Try it yourself

Terminal

All lessons in The OSI Model

1Why Layers

The Layering IdeaSeven LayersNumbers and NamesRecap - The Stack

4The Network Layer

IP and TTLPing and ICMPRouting TablesRecap - Layer Three

7Encapsulation

Wrapping DataHeaders EverywhereReading a CaptureRecap - Follow the Wrap

2The Physical Layer

Bits on a WireHow Long Will It TakeDuplex and Collisions

5Transport: TCP and UDP

PortsThe TCP HandshakeTCP vs UDPSockets in ActionRecap - Layer Four

8The Journey of a Packet

A Click HappensCrossing the NetworksArriving and ClimbingRecap - End to End

3Data Link and MACs

Frames and MACsReading a MACARPRecap - Layer Two

6The Upper Layers

Session and PresentationThe Application LayerWatching the LayersRecap - Top of the Stack

Practice on your own: Terminal playground