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This is physically separate location within a region
We can pin some services to a specific availability zone.
Not all services can be set in an availbility zone 1 and in an availibility zone 2, for example, storage accounts are actually referred to as zone-redundant services and that means we can configure them in such a way that we pick the region and that’s it → We just pick 1 region. If we choose to make it Zone Redundant, Microsoft is going to replicate that data accross the availability zones with a region.
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3- Availability Sets