Book Image

CCNA Routing and Switching 200-125 Certification Guide

By : Lazaro (Laz) Diaz
Book Image

CCNA Routing and Switching 200-125 Certification Guide

By: Lazaro (Laz) Diaz

Overview of this book

Cisco Certified Network Associate (CCNA) Routing and Switching is one of the most important qualifications for keeping your networking skills up to date. CCNA Routing and Switching 200-125 Certification Guide covers topics included in the latest CCNA exam, along with review and practice questions. This guide introduces you to the structure of IPv4 and IPv6 addresses and examines in detail the creation of IP networks and sub-networks and how to assign addresses in the network. You will then move on to understanding how to configure, verify, and troubleshoot layer 2 and layer 3 protocols. In addition to this, you will discover the functionality, configuration, and troubleshooting of DHCPv4. Combined with router and router simulation practice, this certification guide will help you cover everything you need to know in order to pass the CCNA Routing and Switching 200-125 exam. By the end of this book, you will explore security best practices, as well as get familiar with the protocols that a network administrator can use to monitor the network.
Table of Contents (24 chapters)
4
Subnetting in IPv4
21
Mock Test Questions
22
Assessments

Neighbor and adjacency initialization

This is the very first part of OSPF operations. The router at this point will allocate memory for this function as well as for the maintenance of both the neighbor and topology tables. Once the router discovers which interfaces are configured with OSPF, it will begin sending hello packets throughout the interface in the hope of finding other routers using OSPF.

Let's look at a visual representation:

To be honest a lot more than that happens, especially since we are using Ethernet. Remember this would be considered a broadcast in between the routers so the election needs to run to choose DR and BDR, but you don't have to believe me, let me show you.

Before I configured these routers, I turned on debug ip ospf adj.

00:03:06: OSPF: DR/BDR election on FastEthernet0/0
00:03:06: OSPF: Elect BDR 10.1.1.5
00:03:06: OSPF: Elect DR 10.1.1.6...