2Basic Network Security Concepts

Practice questions →Glossary →

2.1Vulnerabilities of TCP/IP protocols
Each protocol in the TCP/IP suite that underpins the internet has weaknesses because security was not a design goal at the outset. This section covers ARP spoofing (a MITM that hijacks traffic with forged MAC replies), DNS poisoning that corrupts name resolution, DHCP attacks involving address exhaustion or a rogue server, ICMP used for reconnaissance and floods, the TCP SYN flood that overflows connections, and eavesdropped plaintext HTTP—all through the lens of identifying "what attack a packet anomaly represents."
2.2Network addresses and security
Covers the addresses used in networking—the L3 IPv4/IPv6 address and the device-specific L2 MAC address—along with CIDR notation that expresses a range like /24, NAT that translates private IPs to a shared global IP, and the difference between freely assignable private addresses and globally unique public addresses, and it teaches network segmentation as a basic defense that confines damage to an island.
2.3Network infrastructure and technologies
Covers the idea of a security architecture built in layers, along with the DMZ buffer zone that isolates public servers from the internal network, virtualization that creates multiple environments on one physical device, the cloud managed by another company, the decoy honeypot that lures attackers, the proxy server that relays and inspects traffic, and the difference between "detection-only IDS" and "detection-plus-blocking IPS"—so you can identify each one's role.
2.4Secure access and SoHo wireless
Covers secure-access technologies—the ACL that permits/denies traffic, the firewall that controls ingress/egress by tracking state, the VPN that encrypts the path, and NAC that checks a device's posture before connection—and the essentials of securing small-office (SoHo) wireless: the encryption standard (WPA2/WPA3) that is the real defense versus MAC filtering and a hidden SSID that are only supplementary—learned by telling "primary defense or supplement" for each.