2022 Update: If you want a clear technical explanation of the OSI model, click on the cover of my book CCNP Enterprise Certification Study Guide: Implementing and Operating Cisco Enterprise Network Core Technologies for a free preview of Chapter 1 which explains each layer of the OSI model in intricate detail. I …

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You probably know the popular Google DNS server IP addresses by heart: 8.8.8.8 and 8.8.4.4. Before those were around you might have even used Level3’s 4.2.2.1 and 4.2.2.2. Of course, everyone else uses these too, which means these popular servers are under a pretty heavy load. Fortunately, there are faster public DNS …

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Cisco CCNA Routing and Switching learning path on Pluralsight