Azure rebooted the server. The bank never noticed.
How update domains let Microsoft patch the hosts under your VMs without dropping a single customer.
What you'll learn
- How Azure reboots hosts one update domain at a time
- Why the load balancer always has a healthy VM to use
- Update domain versus fault domain, in one line
Share this passage
Drawing…
Understand it one step at a time
The short runs these in order in about 57 seconds. Here they are written out — pick any step to jump the short straight to it.
9,400 customers. One payments app
A retail banking app on Azure, 9,400 customers active right now. Transfers are clearing normally — nobody is thinking about the servers underneath.
Frequently asked questions
- What is an Azure update domain?
- A group of VMs that Azure reboots together during planned maintenance. An availability set spreads VMs across multiple update domains, so maintenance takes them down one group at a time rather than all at once.
- What's the difference between an update domain and a fault domain?
- A fault domain groups VMs by shared hardware — the same rack, power and network switch, which fail together unplanned. An update domain groups VMs by planned-maintenance timing. They protect against different kinds of interruption.
Free app · no app store
These are built for a phone
Every short is drawn at full portrait height, the shape a phone already is. Installed, it opens full-bleed with no address bar across the top — and the whole library reads offline.
Read deeper on Azure
Twenty seconds gets the shape of an idea across. These go into how it behaves in production.
-
AI Bot Attacks on a Mobile App Login, and How Azure Stops Them
A script tries 8,000 passwords a minute against your login API at 3am. Rate limiting, smart lockout and Defender for Cloud make speed the losing move.
-
Azure Key Vault Explained: The One Secret Tutorials Never Remove
Moving every secret into Key Vault leaves exactly one behind: the credential that opens the vault. A managed identity is what removes it.
-
How to Secure a Mobile API on Azure in Five Steps, in the Right Order
HTTPS only, authentication, authorization, secrets and monitoring: five steps to secure a mobile API on Azure, and why the order carries most of the value.
More shorts
-
Azure
Money debited. Order failed.
10 steps · 56s
-
Azure
One tap. Two orders.
10 steps · 57s
-
Azure
1.6 million downloads. One photo.
10 steps · 58s
Get new posts by email
New technical articles, Azure AI and GitHub Copilot updates, and upcoming events. No spam, unsubscribe anytime.
MSDEVBUILD
/ blog Multi-Stack Dev Build · by Suthahar Azure