1. Introduction

For the problems DOWN, UNREACH, WARN, CRIT or UNKNOWN Checkmk distinguishes two possible states: unhandled and icon ack handled. A handled (acknowledged) problem indicates that the issue is known and that somebody is attending to it.

If a problem has been acknowledged, then…​

  • …​ it will be identified with a icon ack symbol,

  • …​ it will no longer appear as Unhandled in the Overview snap-in,

  • …​ no further notifications will be sent.

Additionally, problems can be systematically identified in views as being acknowledged or unacknowledged via the Icon for displaying the filter bar. filter Problem acknowledged.

2. The Acknowledgement procedure

Problems are acknowledged via commands on the affected hosts/services. Acknowledgements can be removed in the same way.

basics ackn acknowledge

Advice for these options:


An acknowledgement is normally valid until the next status change. If for example, a service has been acknowledged with a WARN status, and later changes to CRIT, the acknowledgement will be automatically-removed. Activating sticky will retain the acknowledgement until an OK or an UP status is received.

send notification

All contacts assigned to the host/service whom are configured to be notified for the Acknowledgement of host/service problem will be sent a notification.

persistent comment

With this option your commentary will not be automatically deleted if the acknowledgement disappears or is removed. Commentaries entered in this way must be manually deleted later (see the end of this chapter).

Expire acknowledgement after …​

Commercial editions: With this option you can set a time limit for retaining the acknowledgement. When the specified time limit expires the acknowledgement is automatically deleted, even if the host/service is not yet in an OK or an UP status.


You can include a URL such as in this field, which will be replaced by a clickable link.

3. Acknowledgements in the GUI

In the Checkmk web interface there are several possibilities for displaying acknowledgements.

In all host and service views, acknowledged problems are identified by two symbols:

icon ack

This symbol identifies an acknowledgement

icon comment

Clicking on this symbol displays a list with any acknowledgement comments.

Via Monitor > Overview > Comments you can view a list of all comments for hosts and services — including those created through acknowledgements. Comments may be deleted with commands.

basics ackn comments
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