Summary

In this chapter, we talked about data networks in order to identify potential risks and vulnerabilities. We discussed the way that networks operate: layers 1 and 2 carry information directly between attached network elements, layers 3 and 4 carry information from end to end, and layers 5 to 7 implement the network applications.

For layers 1 and 2, we discussed Ethernet protocols and how LAN switches work. Additionally, we looked at VLANs that divide the network virtually into different LANs. We discussed the STP, which prevents loops in the network, and we looked at transmission methods – Unicast, Multicast, and Broadcast.

For layer 3, we talked about ARP and IP. Additionally, we looked at routers and routing protocols that enable the forwarding of packets through the network. For layer 4, we talked about connectivity and reliability, and we discussed TCP, UDP, and the relatively new Google QUIC protocol.

Finally, we looked at tunneling and encapsulation and...