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You're reading from CCNA Security 210-260 Certification Guide Build your knowledge of network security and pass your CCNA Security exam (210-260)

Product type Paperback

Published in Jun 2018

Publisher Packt

ISBN-13 9781787128873

Length 518 pages

Edition 1st Edition

Tools

Cisco

Concepts

IT Certification

Authors (3):

Glen D. Singh

Vinod

Anandh

View More author details

Table of Contents (23) Chapters

Title Page

Packt Upsell

Contributors

Preface

1. Exploring Security Threats FREE CHAPTER

2. Delving into Security Toolkits

3. Understanding Security Policies

4. Deep Diving into Cryptography

5. Implementing the AAA Framework

6. Securing the Control and Management Planes

7. Protecting Layer 2 Protocols

8. Protecting the Switch Infrastructure

9. Exploring Firewall Technologies

10. Cisco ASA

11. Advanced ASA Configuration

12. Configuring Zone-Based Firewalls

13. IPSec – The Protocol that Drives VPN

14. Configuring a Site-to-Site VPN

15. Configuring a Remote-Access VPN

16. Working with IPS

17. Application and Endpoint Security

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Index

The DHCP process

Whenever a client connects to a network, it automatically searches for a Dynamic Host Configuration Protocol (DHCP) server. A DHCP server is used to primarily distribute an IP address, subnet mask, default gateway, and Domain Name System (DNS) server configurations to clients. When the client connects, it broadcasts a DHCPDISCOVER message with a destination MAC address of FFFF.FFFF.FFFF and a destination port of 67

The following is the DHCP four (4) way handshake:

Note

Port 67 is open on the DHCP server. A client uses 68 as the source port.

The DHCP server will respond, send a unicast DHCP Offer message back to the client with potentially usable IP configurations. The client will return a DHCPREQUEST back to the DHCP server, letting the server know it's going to accept the IP configurations from the previous message. They will send a DHCP Acknowledgement message to confirm the IP information the client is going to use for network communication.

Note

A simple method to remember the DHCP process is to use an acronym. So D from Discover, O from Offer, R from Request, and A from Acknowledgement. Putting it all together, it spells DORA.