Search the practice set
126 questions, 454 terms and 400 topics in 20 areas.
60 results for “Design Patterns”
Domain-Driven Design
Modelling software around the business domain, with boundaries drawn where the language of the business changes.
Enterprise Integration Patterns
A catalogue of named, composable messaging patterns — router, translator, aggregator, splitter, filter, dead letter channel — that gives integration work a shared vocabulary.
Privacy by Design
Building privacy protections into a system's structure from the start, rather than adding controls to a design that already collects and keeps everything.
Abstraction
Exposing what a component does while hiding how it does it, so callers depend on the contract rather than the mechanism.
Architecture Cost Model
A calculation, made during design, of what an architecture will cost to run at expected and at peak volume.
Architecture Principle
A durable, agreed rule that constrains design decisions in advance, stated with its rationale and its implications.
Architecture Review Board
A forum that reviews significant designs against standards, risks and strategy before commitment.
Architecture Style
A named, coarse-grained way of organising a whole system, as distinct from a pattern that solves one recurring problem inside it.
Backend for Frontend
A separate, narrow backend per client experience, which aggregates and reshapes downstream services for exactly that client's needs.
CQRS
Separating the model used to change state from the model used to read it, so each can be optimised independently.
Cell-Based Architecture
Partitioning a service into complete, independent copies of itself, each serving a subset of customers, so a failure is bounded to one cell.
Cohesion
The degree to which everything inside one component belongs together and changes for the same reason.
Competing Consumers
Multiple identical consumers reading from one queue, so throughput scales with consumer count and work is distributed automatically.
Coupling
The degree to which one component must know about, or change alongside, another.
Event Sourcing
Storing the full sequence of state-changing events as the system of record, and deriving current state by replaying them.
Event-Driven Architecture
A style in which components communicate by emitting and reacting to facts about what happened, rather than by calling each other.
Fail-Fast vs Fail-Safe
Whether a component should stop immediately on detecting a problem, or continue in a degraded but safe mode — a choice that depends entirely on which outcome is worse.
Design a URL shortener handling 100 million new links per month and 10 billion redirects. Where is the real difficulty?
What the interviewer is testing The classic warm up. What is being assessed is not whether you can shorten a URL — it is whether you do capacity arithmetic befo
A design review presents a new event-driven platform. What cost questions do you ask before approving it?
What the interviewer is testing Whether cost is part of your architecture review or an afterthought handled by finance later, and whether you know the specific
A product catalogue page does 40,000 reads per second against a database that can serve 5,000. Walk me through the caching design, including what happens at 3 AM when the cache is empty.
What the interviewer is testing Whether you can design a cache including its failure modes, rather than saying "put Redis in front of it". The base design Cache
A team shows you a design with eight services. Without knowing the domain, what questions tell you whether the boundaries are right?
What the interviewer is testing Whether you can evaluate a structure from its properties rather than needing to be a domain expert in every system you review. T
An estate has database passwords in environment variables across 200 services. Design the migration to a secrets manager.
Sequence it by risk, not by convenience Phase 0 — stop the bleeding. Secret scanning in CI and on the existing repositories, blocking new commits containing cre
Classify DynamoDB, Spanner and Cassandra under PACELC, and say which half of the classification you would actually design around.
The classifications Store Partition Else Why DynamoDB (default reads) PA EL Serves from any replica; eventually consistent reads avoid a quorum round trip Cassa
Design an order submission API that is safe when the client cannot tell whether its request succeeded. What exactly do you store, and when?
What the interviewer is testing Whether you know that "make it idempotent" is a design with specific failure modes, not a checkbox. The core design The client g
Design the audit logging for a system handling financial transactions. What is logged, where does it go, and what makes it hold up?
What is logged Significant actions only , defined explicitly rather than logging everything — an audit trail nobody can search is not usable evidence: Authentic
Design the network layout for a three-tier application in one cloud region. What are the decisions you cannot easily change later?
What the interviewer is testing Whether you know which network decisions are cheap and which are effectively permanent. This is a knowledge question with a clea
Design the timeout configuration for a request that passes through gateway, orders, pricing and inventory. What numbers, and what rule generates them?
The rule that generates the numbers One budget at the edge, decreasing inward, with room for a retry at exactly one layer. Start from what the caller will actua
In a design review, a respected senior engineer proposes an approach you believe is wrong. The room defers to them. How do you handle it?
What the interviewer is testing Whether you can be effective without authority, which is most of the architect's job. It is also testing whether you assume you
Maersk rebuilt roughly 4,000 servers and 45,000 PCs in about ten days after NotPetya in 2017, and recovered its directory only because one data centre had been offline during the attack. What does this say about DR design?
The case, as publicly reported In June 2017 the NotPetya malware — destructive rather than financially motivated — propagated through Maersk's network, encrypti
Placing an order must reserve stock, charge the card and create a shipment across three services. Design it, and justify why not a distributed transaction.
First: question the boundary A transaction spanning three services often means one invariant has been split across three owners. Before designing a protocol, ch
Product wants to add "customers who bought this also bought" using purchase history. What does privacy by design require here?
The first question is lawful basis, not architecture Purchase history was collected to fulfil orders. Using it for recommendations is a new purpose , and purpos
You are reviewing a design for an internal tool with 200 users. It proposes Kubernetes, microservices, Kafka, a service mesh and CQRS. How do you handle the review?
What the interviewer is testing Judgement, and whether you can push back without alienating a team. Anyone can spot over engineering; the question is what you d
You must choose a data store this week. The product team cannot tell you the expected query patterns or the growth rate. What do you do?
What the interviewer is testing How you behave when the information you would like does not exist — which is the normal condition, not the exception. Both "refu
You must roll out MFA to 40,000 employees. Security wants hardware keys; the service desk fears the call volume. Design the rollout.
The framing that resolves the argument Not every identity carries the same risk, so not every identity needs the same factor. A uniform mandate is what creates
Design Patterns
Reusable solutions at code level, and when they become ceremony.
Architecture Patterns
General material on architectural patterns and their trade-offs.
Coexistence Patterns
Running old and new together for years without corrupting either.
Domain-Driven Design
Ubiquitous language, bounded contexts and context mapping.
Integration Patterns
Routers, translators, splitters, aggregators and dead letter channels.
Legacy Integration Patterns
Anti-corruption layers, adapters and CDC against systems that cannot change.
REST Design
Resources, uniform methods, status codes and statelessness.
Secure API Design
Object-level authorisation, input validation and safe error responses.
Sharding Patterns
Directory versus embedded keys, logical shards and rebalancing.
VPC Design
Address planning, peering and the ranges you can never resize.
API Gateway
A single entry point for policy, routing and protocol translation.
Anti-Corruption Layer
Translating a foreign model at the boundary so it does not leak in.
Architecture Cost Modelling
Pricing a design before building it, at expected and at ten times volume.
Architecture Styles
System-level organising shapes, and how they differ from problem-level patterns.
Backend for Frontend
A narrow backend per client experience, owned by that client's team.
Business KPIs
The numbers a design is ultimately judged against.
Business Understanding
Connecting a design to the outcome that pays for it.
CQRS
Separate models for writing and reading, each optimised for its job.
Cell-Based Architecture
Complete isolated copies each serving a subset of customers.
Cloud Storage
Object, block and file storage, and the access patterns each suits.
Competing Consumers
Scaling throughput with instances, at the cost of ordering.
Ethics in Architecture
Privacy, accessibility, sustainability and the consequences of a design.
Event Sourcing
The event log as the system of record, with state as a projection.
Event-Driven Architecture
Publishing facts, and trading comprehensibility for decoupling.
Facilitation
Running a design session that reaches a decision.