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# Asynchronous versus synchronous operations

A synchronous operation returns a response after the REST API operation completes. For example, `POST /rest/server-profiles` returns a newly created server profile in the response body. An asynchronous operation, such as creating an appliance backup, returns the URI of a task in the Location response header. You can use the task URI to retrieve the current status of the operation, and to obtain the associated resource once the task is complete.

- This is common behavior for all asynchronous APIs.

- You should not depend on any other behavior to get the current status of the operation (such as the content of the returned response body), as it varies from API to API.

  See the API Reference for the behavior of each specific API.

- You should not depend on any other behavior to occur, as it is subject to change in the future, even for the same API version.

Example response header returned from an asynchronous appliance backup REST call

`HTTP/1.1 202 Accepted`

`Date: Tue, 26 Jan 2016 23:19:14 GMT`

`Server: Apache`

`Location: https://<hostname>/rest/tasks/39CE80C4-EF2C-4717-90EA-EF166E83B49F`

`Content-Length: 0`

`cache-control: no-cache`

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