Search the practice set
275 questions, 991 terms and 600 topics in 30 areas.
60 results for “Three Lines Model”
Independent Assurance
Assessment by a function with no involvement in designing or operating the control, which is what makes the assessment worth anything.
Scale Cube
A model describing three independent axes of scaling — cloning, functional decomposition, and data partitioning — each addressing a different limit.
Team Topologies
A model of four team types and three interaction modes used to design an organisation deliberately for a target architecture and flow of change.
Advisory Review Model
Running architecture review as a consulting service that improves designs rather than as an approval gate that permits them.
Architecture Cost Model
A calculation, made during design, of what an architecture will cost to run at expected and at peak volume.
Arrival Rate Model
Driving a load test by requests arriving per second regardless of how the system responds, rather than by a fixed number of virtual users.
C4 Model
A set of four nested diagram levels — context, container, component, code — that keeps each diagram at one consistent level of abstraction.
Capability Model
A structured map of what a business does, independent of how it is organised or which systems support it, used to align technology investment with function.
Cost Accountability Model
The arrangement determining whether teams merely see their costs or are financially charged for them, and the behaviour each produces.
Cost Model Sensitivity
Identifying which assumptions in a cost projection dominate the outcome, so effort goes into the estimates that actually matter.
Embedding Model Migration
The process of moving a corpus to a new embedding model, which requires re-embedding everything because vectors from different models are not comparable.
Execution Model Fit
Matching a workload's traffic shape, duration and state requirements to the execution model that suits it, rather than choosing one model for everything.
Governance Operating Model
The arrangement of decision rights, review points and automated controls through which architectural intent is maintained across an organisation.
Model Card
A structured record of what a model is for, how it was built and where it should not be used — written for the people who will deploy or be affected by it.
Model Context Protocol
An open protocol that standardises how AI applications connect to external tools, data sources and prompts.
Model Inventory
A complete register of models in use with their purpose, owner, risk tier and validation status — the artifact everything else in model governance depends on.
Model Router
Directing each request to a model chosen by the task's difficulty, cost and latency budget, rather than sending everything to the largest model available.
Model Routing
Directing each request to the cheapest model capable of handling it, rather than sending all traffic to the most capable one.
Model Translation Boundary
The layer at which an external system's model is converted into your own, preventing its concepts and accidents from spreading into your domain.
Operating Model
How an organisation arranges people, process, technology and governance to deliver its capabilities, which constrains architecture as strongly as any technical factor.
Platform Team Product Model
Running an internal platform team with product management disciplines — users, roadmap, support, metrics — rather than as an infrastructure function.
Process Model
A representation of how work actually flows through an organisation, distinguished from a capability by describing sequence, actors and handoffs.
A CDC pipeline feeding your warehouse falls three hours behind during a source system's batch job, and the source's transaction log retention is 24 hours. What is the risk and what do you change?
The immediate risk Lag consumes the retention window. At three hours behind against a 24 hour retention, you have 21 hours of margin. If the consumer stops enti
A business unit wants an assistant answering questions from 200,000 internal documents. They ask whether to fine-tune a model or use retrieval. How do you decide?
Retrieval, for this requirement, and the reasoning is not about quality Four properties decide it: Freshness. Documents change. Retrieval reflects a change as s
A dashboard has been wrong for three weeks. Nobody knows which upstream produced the table it reads. What is the governance failure, and what fixes it?
The failures, and there are three 1. No lineage. The question "which upstream produced this?" should be answerable in seconds by following a derived dependency
A deployed model performed well in validation and its business metric has declined over four months. Nothing has been deployed. What do you investigate?
The model did not change; its world did Three distinct causes, and they need different responses: Data drift. The input distribution has moved — a new customer
A document collaboration product needs sharing with individuals, teams, and inherited folder permissions. Which authorization model?
The requirement is relationship shaped The questions this product must answer are: is this user a member of a team that has access to a folder that contains thi
A field application has been live for three months and support reports that engineers occasionally lose completed job reports. What do you investigate?
Suspect last writer wins on a record level merge The pattern fits exactly. Two writers touch the same record — the engineer's device and the office, or two devi
A new CIO asks for a view of "what IT actually supports". You have three weeks. What do you produce and what do you avoid?
Produce a capability map with one thing overlaid Two levels of business capability — perhaps forty boxes — with applications mapped onto them and a single overl
A new platform must serve a public partner API, three internal front-ends with different data needs, and high-volume service-to-service traffic. Choose the API styles and defend the choice.
Resist "pick one" These are three different problems with three different consumers. Standardising on one style optimises for architectural tidiness at the expe
A project is three sprints from launch and no non-functional requirements were ever written down. What do you do?
Do not write a full NFR matrix now There is no time, and most of the design decisions those numbers would have constrained have already been made. Writing twelv
A quarterly board report shows a category down 40%. Investigation finds an upstream system stopped sending a field three months ago. Nothing alerted. What do you change?
Understand why nothing fired The pipeline completed successfully every night. It read the source, applied its transformation, and wrote rows — all of which is w
A service's p99 latency has tripled over three months with no single obvious change. How do you investigate?
Establish the shape before touching anything Is it everything or something? Break the metric down by endpoint, tenant, region, instance and version. A tripling
A team's CI suite fails roughly one run in three for reasons unrelated to the change. Everyone reruns until green. How do you recover the situation?
Recognise what has actually been lost The suite is no longer a gate. Once the team's reflex on red is "rerun", that reflex is applied to genuine failures too, a
A twenty-year-old core system supports most of the business. It is on unsupported technology, three people understand it, and the last replacement attempt was abandoned after two years. Design the programme.
Learn from the abandoned attempt first The most important input is why the last one failed, and the reasons are usually structural rather than technical: a big
A vendor SaaS product embeds a model that scores customers, and its output drives an automated decision in your process. Your model governance framework covers models you build. What do you do?
The obligation does not transfer with the outsourcing You are accountable for the decision. That the scoring is performed by a vendor changes who operates the m
After adding circuit breakers, a partial outage now lasts three times longer than it used to. What is likely happening?
The likely mechanism: breaker oscillation The dependency is recovering slowly — it can serve some traffic but not full load. The breaker opens, waits out its co
An internal AI assistant gives confidently wrong answers. The team wants to upgrade to a better model. What do you check first?
Establish whether the model ever saw the right content Log the retrieved chunks alongside each answer, then take the wrong answers and check: was the correct so
An organisation is starting cloud adoption. Three teams want to deploy next month. What must exist first, and what can wait?
What must exist before anything reaches production Account structure. Separation by environment and by workload, because an account is the strongest isolation b
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
Finance wants a three-year commitment on cloud spend for the discount. Engineering is nervous. How do you advise?
Commit to the floor, not to the forecast The safe commitment is the portion of usage that will exist regardless of what happens: the steady baseline, evidenced
Finance wants to cut cloud spend by committing to one-year and three-year reservations. What do you commit to, and what could go wrong?
What the interviewer is testing Whether you can turn a blunt cost mandate into a portfolio decision with a stated risk, rather than either refusing it or over c
Instagram served 14 million users with three engineers on Django and Postgres. What does that tell you about how to choose an architecture for a new product?
What the interviewer is testing Whether you can identify the binding constraint. For most products it is not traffic. What Instagram actually did Their 2011 pos
Leadership wants to consolidate a warehouse, a data lake and three departmental marts into a lakehouse. How do you scope and sequence this?
Establish the actual driver "Consolidate onto a lakehouse" is a solution. The driver is usually one of: cost of maintaining several copies, inconsistency betwee
One availability zone becomes unavailable. Walk through what happens to a typical three-tier application and what you would have changed.
What survives and what does not Load balancer — regional, survives, and stops routing to targets in the failed zone once health checks fail. Note the detection
Partner integrations take four months from contract signature to production traffic. Engineering says the work is three days. Where does the time go and how do you cut it?
Map the elapsed time honestly The engineering estimate is correct and irrelevant. The four months are: Legal and contractual review. Security questionnaires and
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
Three Lines Model
Ownership, oversight and independent assurance, and where architecture sits in it.
Assurance, Audit & Model Risk
General material on assurance, architectural governance and risk oversight.
C4 Model
Context, container, component and code as four separate diagrams.
Model Documentation
Model cards, intended use, limitations, and the record a regulator will ask for.
Model Evaluation & Red-Teaming
Adversarial testing of a probabilistic system with no fixed expected output.
Model Risk Management
Inventory, validation, monitoring and challenge for models that make consequential decisions.
Model Selection
Capability, latency, cost and the evaluation that decides between them.