diff --git a/doc/15-troubleshooting.md b/doc/15-troubleshooting.md
index c5442f0ae91..02f6ef0721a 100644
--- a/doc/15-troubleshooting.md
+++ b/doc/15-troubleshooting.md
@@ -1393,6 +1393,56 @@ $ curl -k -s -u root:icinga -H 'Accept: application/json' -X POST 'https://local
```
+#### Agent Hosts with Command Endpoint require a Zone
+
+2.11 fixes bugs where agent host checks would never be scheduled on
+the master. One requirement is that the checkable host/service
+is put into a zone.
+
+By default, the Director puts the agent host in `zones.d/master`
+and you're good to go. If you manually manage the configuration,
+the config compiler now throws an error with `command_endpoint`
+being set but no `zone` defined.
+
+In case you previously managed the configuration outside of `zones.d`,
+follow along with the following instructions.
+
+The most convenient way with e.g. managing the objects in `conf.d`
+is to move them into the `master` zone.
+
+First, verify the name of your endpoint's zone. The CLI wizards
+use `master` by default.
+
+```
+vim /etc/icinga2/zones.conf
+
+object Zone "master" {
+ ...
+}
+```
+
+Then create a new directory in `zones.d` called `master`, if not existing.
+
+```
+mkdir -p /etc/icinga2/zones.d/master
+```
+
+Now move the directory tree from `conf.d` into the `master` zone.
+
+```
+mv conf.d/* /etc/icinga2/zones.d/master/
+```
+
+Validate the configuration and reload Icinga.
+
+```
+icinga2 daemon -C
+systemctl restart icinga2
+```
+
+Another method is to specify the `zone` attribute manually, but since
+this may lead into other unwanted "not checked" scenarios, we don't
+recommend this for your production environment.
### Cluster Troubleshooting Config Sync
@@ -1485,6 +1535,100 @@ In order to solve this problem, remove the mentioned files from `zones.d` and us
of syncing plugin binaries to your satellites and agents.
+#### Zones in Zones doesn't work
+
+The cluster config sync works in the way that configuration
+put into `/etc/icinga2/zones.d` only is included when configured
+outside in `/etc/icinga2/zones.conf`.
+
+If you for example create a "Zone Inception" with defining the
+`satellite` zone in `zones.d/master`, the config compiler does not
+re-run and include this zone config recursively from `zones.d/satellite`.
+
+Since v2.11, the config compiler is only including directories where a
+zone has been configured. Otherwise it would include renamed old zones,
+broken zones, etc. and those long-lasting bugs have been now fixed.
+
+A more concrete example: Masters and Satellites still need to know the Zone hierarchy outside of zones.d synced configuration.
+
+**Doesn't work**
+
+```
+vim /etc/icinga2/zones.conf
+
+object Zone "master" {
+ endpoints = [ "icinga2-master1.localdomain", "icinga2-master2.localdomain" ]
+}
+```
+
+```
+vim /etc/icinga2/zones.d/master/satellite-zones.conf
+
+object Zone "satellite" {
+ endpoints = [ "icinga2-satellite1.localdomain", "icinga2-satellite1.localdomain" ]
+}
+```
+
+```
+vim /etc/icinga2/zones.d/satellite/satellite-hosts.conf
+
+object Host "agent" { ... }
+```
+
+The `agent` host object will never reach the satellite, since the master does not have
+the `satellite` zone configured outside of zones.d.
+
+
+**Works**
+
+Each instance needs to know this, and know about the endpoints first:
+
+```
+vim /etc/icinga2/zones.conf
+
+object Endpoint "icinga2-master1.localdomain" { ... }
+object Endpoint "icinga2-master2.localdomain" { ... }
+
+object Endpoint "icinga2-satellite1.localdomain" { ... }
+object Endpoint "icinga2-satellite2.localdomain" { ... }
+```
+
+Then the zone hierarchy as trust and also config sync inclusion is required.
+
+```
+vim /etc/icinga2/zones.conf
+
+object Zone "master" {
+ endpoints = [ "icinga2-master1.localdomain", "icinga2-master2.localdomain" ]
+}
+
+object Zone "satellite" {
+ endpoints = [ "icinga2-satellite1.localdomain", "icinga2-satellite1.localdomain" ]
+}
+```
+
+Once done, you can start deploying actual monitoring objects into the satellite zone.
+
+```
+vim /etc/icinga2/zones.d/satellite/satellite-hosts.conf
+
+object Host "agent" { ... }
+```
+
+That's also explained and described in the [documentation](06-distributed-monitoring.md#distributed-monitoring-scenarios-master-satellite-agents).
+
+The thing you can do: For `command_endpoint` agents like inside the Director:
+Host -> Agent -> yes, there is no config sync for this zone in place. Therefore
+it is valid to just sync their zones via the config sync.
+
+> **Summary**
+>
+> With using the Director, its cluster zones and agent hosts, you are safe.
+>
+> Manage the master/satellite instances outside in zones.conf and import
+> them via kickstart wizard.
+
+
### Cluster Troubleshooting Overdue Check Results
If your master does not receive check results (or any other events) from the child zones
diff --git a/doc/16-upgrading-icinga-2.md b/doc/16-upgrading-icinga-2.md
index 88c7d828402..2ffed83f2b4 100644
--- a/doc/16-upgrading-icinga-2.md
+++ b/doc/16-upgrading-icinga-2.md
@@ -29,14 +29,22 @@ The rewrite of our core network stack for cluster and REST API
requires newer Boost versions, specifically >= 1.66. For technical
details, please continue reading in [this issue](https://github.com/Icinga/icinga2/issues/7041).
-The package dependencies have been updated for RPM/DEB already.
-On platforms where EPEL or Backports cannot satisfy this dependency,
-we provide Boost as package on our [package repository](https://packages.icinga.com):
+Distribution | Repository providing Boost Dependencies
+---------------------|-------------------------------------
+RHEL/CentOS 7 | [EPEL repository](02-installation.md#package-repositories-rhel-epel)
+RHEL/CentOS 6 x64 | [packages.icinga.com](https://packages.icinga.com)
+Fedora | Fedora Upstream
+Debian 10 Buster | Debian Upstream
+Debian 9 Stretch | [Backports repository](02-installation.md#package-repositories-debian-backports) **New since 2.11**
+Debian 8 Jessie | [packages.icinga.com](https://packages.icinga.com)
+Ubuntu 18 Bionic | [packages.icinga.com](https://packages.icinga.com)
+Ubuntu 16 Xenial | [packages.icinga.com](https://packages.icinga.com)
+SLES 15 | SUSE Upstream
+SLES 12 | [packages.icinga.com](https://packages.icinga.com) (replaces the SDK repository requirement)
-* SLES 12 (this replaces the SDK requirement)
-* CentOS 6 x64
-* Debian Jessie
-* Ubuntu Xenial/Bionic
+On platforms where EPEL or Backports cannot satisfy this dependency,
+we provide Boost as package on our [package repository](https://packages.icinga.com)
+for your convenience.
After upgrade, you may remove the old Boost packages (1.53 or anything above)
if you don't need them anymore.
@@ -144,6 +152,22 @@ please let us know with an issue on GitHub.
### Cluster
+#### Agent Hosts with Command Endpoint require a Zone
+
+2.11 fixes bugs where agent host checks would never be scheduled on
+the master. One definite requirement is that the checkable host/service
+is put into a zone.
+
+By default, the Director puts the agent host in `zones.d/master`
+and you're good to go. If you manually manage the configuration,
+the config compiler now throws an error with `command_endpoint`
+being set but no `zone` defined.
+
+The most convenient way with e.g. managing the objects in `conf.d`
+is to move them into the `master` zone. Please continue in the
+[troubleshooting docs](#troubleshooting-cluster-command-endpoint-errors-agent-hosts-command-endpoint-zone)
+for further instructions.
+
#### Config Sync
2.11 overhauls the cluster config sync in many ways. This includes the
@@ -186,6 +210,30 @@ and trigger reload loops. In order to prevent such harm in production,
use infrastructure tools such as Foreman, Puppet, Ansible, etc. to install
plugins on the masters, satellites and agents.
+##### Config Sync: Zones in Zones
+
+The cluster config sync works in the way that configuration
+put into `/etc/icinga2/zones.d` only is included when configured
+outside in `/etc/icinga2/zones.conf`.
+
+If you for example create a "Zone Inception" with defining the
+`satellite` zone in `zones.d/master`, the config compiler does not
+re-run and include this zone config recursively from `zones.d/satellite`.
+
+Since v2.11, the config compiler is only including directories where a
+zone has been configured. Otherwise it would include renamed old zones,
+broken zones, etc. and those long-lasting bugs have been now fixed.
+
+Please consult the [troubleshoot docs](15-troubleshooting.md#troubleshooting-cluster-config-zones-in-zones)
+for concrete examples and solutions.
+
+> **Note**
+>
+> With using the Director, its cluster zones and agent hosts, you are safe.
+>
+> Manage the master/satellite instances outside in zones.conf and import
+> them via kickstart wizard.
+
#### HA-aware Features