DDoS refers to the steady bombardment of concurrent data requests to a server from multiple compromised systems. Generally, Botnet devices are used to accomplish a DDoS attack successfully.
Big Data means data that is too diverse, fast-changing or voluminous for conventional techniques, skills, and infrastructure to address efficiently. You can say that the volume, velocity or variety of data is too high. This data can be structured, semi-structured or unstructured.
Wide Area Network, commonly known as WAN is a computer network that extends over a relatively large geographical area. The largest WAN in existence is the Internet. A WAN functions like a Local Area Network (LAN), just on a larger scale.
A network adapter is the unit of a computer's hardware that a computing device employs for interfacing over a network with another computer. It could be wired or wireless.
Network performance refers to measures of service quality of a network as seen by the end-user. Network speed is sometimes synonymous with the performance of a network. Bandwidth, latency, jitter are some of the metrics which affect network performance.