The database administrator role is about keeping data safe, available, and fast. Interviews test backups and recovery, performance tuning, indexing, replication, security, and high availability. Here are the DBA interview questions that actually get asked. (See also our DBMS and SQL guides.)
Backups & recovery
- Types of backups — full, incremental, differential.
- What is point-in-time recovery?
- RPO and RTO — how do they shape your backup strategy?
- How do you test that backups actually work?
Performance & indexing
- How do you find and fix a slow query (execution plans)?
- Indexing strategy — when does an index help and when does it hurt?
- Clustered vs non-clustered indexes.
- What causes deadlocks and how do you resolve them?
Availability & security
- Replication — primary/replica, synchronous vs asynchronous.
- Sharding and partitioning for scale.
- High availability and failover.
- Database security — access control, encryption, auditing.
How to prepare
DBA rounds probe recovery and tuning scenarios verbally. Practise explaining backup strategy and query tuning out loud. Greenroom runs spoken technical interviews that follow up on your reasoning. Pair it with our DBMS and SQL guides.
Frequently asked questions
What questions are asked in a DBA interview?
DBA interviews cover backups and recovery (full/incremental/differential backups, point-in-time recovery, RPO/RTO, testing backups), performance tuning (finding slow queries with execution plans, indexing strategy, clustered vs non-clustered indexes, deadlocks), availability (replication, sharding, partitioning, failover), and security (access control, encryption, auditing).
What is the difference between full, incremental and differential backups?
A full backup copies all data. An incremental backup copies only data changed since the last backup of any type, making it fast and small but requiring the full chain to restore. A differential backup copies all data changed since the last full backup, growing over time but needing only the full backup plus the latest differential to restore. The choice balances backup speed, storage and restore complexity.
How do you fix a slow query as a DBA?
Start by examining the query's execution plan to find table scans, missing indexes or expensive operations. Add or adjust indexes to support the query's filters and joins, rewrite inefficient SQL, update statistics, and consider partitioning for large tables. Verify improvements by re-checking the plan and timings. The goal is to reason from the execution plan rather than guess.
How should I prepare for a DBA interview?
Focus on backups and recovery, performance tuning and indexing, replication and high availability, and database security, with a 'protect the data first' mindset. Practise explaining your backup and recovery strategy and how you'd tune a slow query out loud with a voice-based mock interview that follows up, since DBA rounds probe recovery and tuning scenarios.