Chapter 4
Confidentiality (only authorized access), Integrity (data is accurate and unaltered), Availability (data is accessible when needed).something you know (password), something you have (OTP token), something you are (fingerprint). MFA drastically reduces account compromise risk.SSL (Secure Sockets Layer) is deprecated; TLS (Transport Layer Security) is the current standard. Both use asymmetric key exchange then symmetric encryption.Risk = Threat Γ Vulnerability Γ Asset Value. Strategies: accept (low risk), mitigate (add controls), transfer (insurance), avoid (stop the activity).Subject-oriented (organized by subject like sales), Integrated (consistent formats), Time-variant (stores historical snapshots), Non-volatile (data is only loaded, not updated).IaaS (Infrastructure as a Service β rent VMs, storage; e.g., AWS EC2), PaaS (Platform as a Service β deploy apps without managing OS; e.g., Heroku, Google App Engine), SaaS (Software as a Service β use software over internet; e.g., Gmail, Salesforce). IaaS > PaaS > SaaS in control level.Map β splits input, applies function to each chunk producing key-value pairs. Phase 2: Shuffle/Sort β groups by key. Phase 3: Reduce β aggregates values per key. Used in Hadoop.HDFS (Hadoop Distributed File System β stores data across nodes with replication), YARN (resource manager), MapReduce (processing engine). Default HDFS replication factor: 3.Volume (massive scale), Velocity (speed of generation), Variety (structured/unstructured/semi-structured), Veracity (data quality), Value (actionable insights).f(n) = g(n) + h(n) where g(n) = cost from start to node n, h(n) = estimated cost from n to goal (heuristic). A* is optimal if h(n) is admissible (never overestimates).Sigmoid (0 to 1, used in binary classification output), ReLU (max(0,x), avoids vanishing gradient, most popular in hidden layers), Tanh (-1 to 1), Softmax (multi-class output, probabilities sum to 1).Selection (choose best individuals based on fitness), Crossover (combine two parents to create offspring), Mutation (randomly alter genes). The fitness function evaluates solution quality.IF temperature > 38 AND cough = yes THEN infection = probable. The inference engine pattern-matches these rules.