DNS (Domain Name System) is the service that resolves human-readable domain names to IP addresses using record types such as A, AAAA, CNAME, MX, and PTR. DNS resolution failures are a common network-services issue Network+ expects you to diagnose.
The OSI model is a seven-layer conceptual framework (Physical, Data Link, Network, Transport, Session, Presentation, Application) that standardizes how network functions interact.
Subnetting is the practice of dividing an IP network into smaller logical subnetworks using a subnet mask or CIDR prefix.
A VLAN (Virtual Local Area Network) is a logical segmentation of a switched network that groups devices independently of physical location.
The Spanning Tree Protocol (STP) is a Layer 2 protocol that prevents switching loops by blocking redundant paths while keeping a loop-free active topology.
OSPF (Open Shortest Path First) is a link-state interior gateway routing protocol that builds a map of the network and computes shortest paths using cost.
NAT (Network Address Translation) is a technique that maps private IP addresses to one or more public addresses at a router boundary.
DHCP (Dynamic Host Configuration Protocol) is a service that automatically assigns IP addresses, subnet masks, gateways, and DNS servers to clients through a discover-offer-request-acknowledge exchange.
DNS (Domain Name System) is the service that resolves human-readable domain names to IP addresses using record types such as A, AAAA, CNAME, MX, and PTR.
Wi-Fi is the common name for the IEEE 802.
Zero trust is a security model that assumes no user or device is inherently trusted, requiring continuous verification and least-privilege access regardless of network location.
Network segmentation is the practice of splitting a network into isolated zones — using VLANs, subnets, DMZs, or ACLs — to limit lateral movement and contain threats.
Traceroute (traceroute on Linux, tracert on Windows) is a diagnostic tool that reveals the hop-by-hop path packets take to a destination and the latency at each hop.
A duplex mismatch is a misconfiguration where two link partners disagree on half- vs full-duplex operation, causing late collisions, CRC errors, and severe throughput loss.