Ravindra BagaleCourses & study guides

Chapter 2: The OSI Model and TCP/IP Model

Common Mistakes I See Students Make

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  • Mixing up the order of layers or placing TCP at the network layer. Use the mnemonic and practise drawing it.
  • Saying "a switch works at Layer 3". A normal switch works at Layer 2 (MAC addresses); a router works at Layer 3 (IP).
  • Thinking HTTPS is a different layer from HTTP. HTTPS = HTTP (Layer 7) carried over TLS (Layer 6 in OSI terms).
  • Forgetting DNS in the website walk-through. Without DNS, the browser does not even know which IP to connect to.
  • Assuming ping failure means the server is down. ICMP may simply be blocked by the security group.