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CCNA Routing and Switching 200-125 Certification Guide

You're reading from   CCNA Routing and Switching 200-125 Certification Guide The ultimate solution for passing the CCNA certification and boosting your networking career

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Product type Paperback
Published in Oct 2018
Publisher Packt
ISBN-13 9781787127883
Length 504 pages
Edition 1st Edition
Tools
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Author (1):
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Lazaro (Laz) Diaz Lazaro (Laz) Diaz
Author Profile Icon Lazaro (Laz) Diaz
Lazaro (Laz) Diaz
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Toc

Table of Contents (24) Chapters Close

Preface 1. Internetworking Models FREE CHAPTER 2. Ethernet Networking and Data Encapsulations 3. Introducing the TCP/IP 4. Subnetting in IPv4 5. Variable Length Subnet Mask and Route Summarization 6. The IOS User Interface 7. Managing the Cisco Internetwork 8. Managing Cisco Devices 9. The IP Routing Process 10. The IPv6 Protocol 11. Introduction to IPv6 Routing 12. Switching Services and Configurations 13. VLANs and Inter-VLAN Routing 14. Introduction to the EIGRP Routing Protocol 15. The World of Open Shortest Path First (OSPF) 16. Border Gateway Protocol 17. Access-Control List 18. Network Address Translation 19. Wide Area Networks 20. Advanced Networking Topics 21. Mock Test Questions
22. Assessments
23. Other Books You May Enjoy

Rommon or ROM monitor mode

I have already explained how we could get into rommon by using a break command to interrupt the boot sequence and that would take us to ROM's monitor mode. But we only used it to change register settings, and that was very simple.

But what would you do if you come into work on Monday and found the following screen staring you in the face, telling you that it could not find a bootable device.

Look at this screenshot:

You would be like, what in the world? At this moment, you need to take a breath and think, OK, when I left, all was well and everything was copied to NVRAM and backed up to a TFTP server. It could be possible that you changed the registry to boot to rommon by fat finger the keyboard.

So, what you first try is changing the registry to 0x2102 and resetting to see whether it boots fine, and it does not.

What is happening is your IOS got...

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