Almost every breach has a network component, which is why almost every security role has a network-fluency requirement. The good news: the parts that matter at the entry level are stable and well-documented.
TCP/IP fundamentals
OSI model, TCP vs UDP, the three-way handshake, DNS, NAT, ARP. Each of these will show up in an interview at least once.
Defense mechanisms
Firewalls (stateful vs stateless), IDS/IPS, segmentation, VPN basics, and TLS. Know the trade-offs each one introduces.
What to practice
Wireshark on your own traffic. Build a small home lab with two VMs and a virtual firewall. Capture, analyze, and explain.
The bottom line
Network security is one of the few areas where lab work compounds quickly. Spend a weekend with Wireshark and you’ll outpace most résumés in the pile.
