AZ-400 prerequisites: what you need first

You can book and sit AZ-400 without holding any other certification, as far as Microsoft’s exam page is concerned: it states no booking restriction. The credential is different. Microsoft’s page for Microsoft Certified: DevOps Engineer Expert says that to earn it you “must earn at least one of” two associate certifications, Azure Administrator Associate or Azure Developer Associate, in addition to passing AZ-400. As of 30 October 2026 the certification page still shows that rule, with a count of two prerequisite certifications. The Azure Developer Associate page, however, now carries a warning that the certification and its renewal assessment are retired. For a new candidate the practical route is therefore AZ-104.

What Microsoft says

There are two separate things to separate here.

The certification requirement. Pass AZ-400 and hold one qualifying associate certification. The exam and the credential are not the same event: you can pass AZ-400 first and earn the associate certification later, but the DevOps Engineer Expert credential is only awarded once both are in place. The shorter version of this rule, with exam tips, is in AZ-400 prerequisites and exam tips.

The experience expectation. The exam page describes a developer or infrastructure administrator, and says you “must have experience both administering and developing in Azure, with strong skills in at least one of these areas”. It adds that you “should also have experience implementing both GitHub and Azure DevOps solutions”. Microsoft does not publish a number of years.

I could not find a statement on any Microsoft page about what happens if the Azure Developer Associate certification is held by someone who earned it before retirement. Check your own transcript and the certification page before relying on it.

The background that helps

Git and source control

Branching, merging, pull requests, rebasing, and what a merge conflict actually is. If you only use a graphical client, practise the command line once; the source control guide assumes you know the basics.

Pipelines and YAML

This is the heaviest area of the exam, so it is also the most important background. You should have written or edited a pipeline: triggers, stages, jobs, variables, secrets, and artifacts. YAML indentation errors are a common source of wrong answers, because options often differ in a single line.

Azure administration

A DevOps engineer deploys to Azure, so you need to know what a resource group, a virtual network, an App Service plan, a container registry and a managed identity are. The associate certification requirement exists for this reason.

Scripting and infrastructure as code

PowerShell, Bash or the Azure CLI, plus ARM templates, Bicep or Terraform. You do not need to write them from memory, but you should read a template and say what it deploys.

Security and monitoring basics

Secret handling, least privilege, dependency and code scanning, and reading logs and metrics. These are smaller domains but they appear in pipeline scenarios as well.

What you do not need

Self-check

1. Can you write a multi-stage pipeline that builds, tests and deploys, and say how each stage gets its secrets?
2. Can you explain why a branch policy is not the same as a pipeline check?
3. Can you read a short Bicep file and name what it creates?
4. Do you know how a pipeline authenticates to Azure without storing a password?
5. Have you worked in both GitHub and Azure DevOps, even in a free lab?

Two or more gaps: spend two weeks on labs first, then follow the study plan.

Where it leads

AZ-400 is the single exam for the DevOps Engineer Expert credential. See AZ-400 versus AZ-104 if you are deciding which to take first, and the exam format for the mechanics.