Data engineering fundamentals: Building / designing data pipelines, ETL/ELT, data ingestion, batch vs real-time, data lake vs data warehouse, data modeling, data governance. (Matches responsibilities from the data-engineer job ad at Sonatel.) Senjob Programming / Scripting: Probably Python, SQL, maybe Scala or Java, depending on their stack. Big Data / Distributed Data: Given Sonatel’s size and data scale (large telco, many users), they might ask about distributed processing frameworks — e.g., Spark, Hadoop, streaming, data partitioning, resource management.