System Design Interview Preparation
Beginner to advanced, with interactive simulators and full design case studies.
Python Full-Stack Interview Preparation
Master backend + frontend questions with real-world cases.
AI/ML Engineer Interview Preparation
ML, deep learning, LLMs, RAG, MLOps and system design - with mock interviews.

Navigate by Range

Q&A Python-1-5
Q&A Python-6-10
Q&A Python-11-15
Q&A Python-16-20
Q&A Python-21-25
Q&A Python-26-30
Q&A Python-31-35
Q&A Python-36-40
Q&A Python-41-45
Q&A Python-46-50
Q&A Python-51-55
Q&A Python-56-60
Q&A Python-61-65
Q&A Python-66-70
Q&A Python-71-75
Q&A Python-76-80
Q&A Python-81-85
Q&A Python-86-90
Q&A DB-MySQL-1-5
Q&A DB-MySQL-6-10
Q&A DB-MySQL-11-15
Q&A DB-MySQL-16-20
Q&A DB-MySQL-21-25
Q&A DB-MySQL-26-30
Q&A DB-MySQL-31-35
Q&A DB-MySQL-36-40
Q&A DB-MySQL-41-45
Q&A DB-MySQL-46-50
Q&A Django-1-5
Q&A Django-6-10
Q&A Django-11-15
Q&A Django-16-20
Q&A Django-21-25
Q&A Django-26-30
Q&A Django-31-35
Q&A Django-36-40
Q&A Django-41-45
Q&A Django-46-50
Q&A FastAPI-01-05
Q&A FastAPI-06-10
Q&A FastAPI-11-15
Q&A FastAPI-16-20
Q&A FastAPI-21-25
Q&A FastAPI-26-30
Q&A FastAPI-31-35
Q&A FastAPI-36-40
Q&A FastAPI-41-45
Q&A FastAPI-46-50
Q&A FastAPI-51-55
Q&A FastAPI-56-60
Q&A FastAPI-61-65
Q&A HTML-01-05
Q&A HTML-06-10
Q&A HTML-11-15
Q&A HTML-16-20
Q&A CSS-01-05
Q&A CSS-06-10
Q&A CSS-11-15
Q&A CSS-16-20
Q&A JavaScript-1-5
Q&A JavaScript-6-10
Q&A JavaScript-11-15
Q&A JavaScript-16-20
Q&A JavaScript-21-25
Q&A JavaScript-26-30
Q&A JavaScript-31-35
Q&A JavaScript-36-40
Q&A JavaScript-41-45
Q&A JavaScript-46-50
Q&A React-1-5
Q&A React-6-10
Q&A React-11-15
Q&A React-16-20
Q&A React-21-25

Python Full-Stack GlossaryReplication lag

Databases

Replication lag

The delay before a write on the primary becomes visible on a replica.

Why interviewers ask about it

The concrete bug is read-after-write: a user saves and the change appears to vanish. The fix is routing that read to the primary or pinning the session.