IBM Cloud Platforms & Architecture interview questions

The services-and-enterprise interview staple. There is a defensible answer and it is not 'always re-platform': the decision is a function of change tolerance, deadline reality and what the workload is worth.

Allow-listing egress starts free with security groups and ends with TLS-breaking appliances. Each rung costs latency, money and political capital, and knowing where to stop is the actual test.

Four options with genuinely different costs, and the requirement is usually narrower than it first sounds. Establish whether it is about the network path, the data residency, or the provider's retention terms, because those need different answers.

Multi-AZ is the answer and the reason matters more than the acronym. Each tier fails differently, and the database is the one where high availability means a failover with a real gap, not zero interruption.

One is layer 4 and regional, one is layer 7 and regional, one is layer 7 and global. Answer on those two axes and the choice makes itself, including when you need two of them together.

Four levels, and the two that matter operationally are the subscription, where quotas and billing live, and the resource group, which is the unit you delete. Getting the boundaries wrong is expensive to unpick later.

Service principal with a client secret is the answer people give and the one that leaves a credential in a config file. Managed identity is the same object with the secret handled by the platform.

Turns the standard autoscaling definition into the problem it actually causes. Almost every candidate can define an HPA; far fewer can say why theirs did not save them.

Ask whether Multi-AZ means a DB instance or a DB cluster. One has a non-readable standby; the other has two readers. That distinction decides whether the proposal can relieve the primary.

Two questions settle most of it: how much of the machine do you want to own, and is the workload request-shaped or long-running. Fargate is a way of running containers rather than a competitor to ECS and EKS, which is the distinction people get wrong.

Two structural differences matter more than any service mapping: the VPC is global rather than regional, and permissions are granted to members on resources through a hierarchy rather than attached to identities.

The comparison table is easy to recite and explains nothing about the failure the difference actually causes. The ephemeral port range is the whole answer.

The question that separates console users from people who have debugged a permissions failure across accounts. Evaluation order is deterministic and knowing it makes AccessDenied readable.

A design question with a clear answer at this scale, and the reasoning is what scores. The three options solve different problems and peering and Transit Gateway connect networks while PrivateLink exposes services.

Most candidates can sell serverless. The question asks you to argue against it, which needs a real understanding of the execution model rather than the marketing.

Trace the route and return path before changing rules. First establish whether the failing connection uses IPv4, IPv6 or a private service endpoint.

A question that sounds introductory and turns on one distinction: what you stop operating, and what you start paying for instead. The answer is three mechanical differences and one economic one.

S3 access failures are rarely about the bucket policy alone. The caller, object ownership and network path determine which authorization checks apply. Start with the failed request and trace changes across those boundaries.