diff --git a/docs/home-network/services/pi-hole-dns-server.md b/docs/home-network/services/pi-hole-dns-server.md
index f8b5be7..e7dadad 100644
--- a/docs/home-network/services/pi-hole-dns-server.md
+++ b/docs/home-network/services/pi-hole-dns-server.md
@@ -17,23 +17,26 @@ running on raspberrypi.)
 
 ## Local DNS
 
+Local network domains use `.home` instead of `.local` because `.local` collides
+with device's built-in systems for resolving `.local` domains automagically.
+
 ### A records
 
-Local A records map machine domain names to their IP address.
+`.home` A records map machine domain names to their IP address.
 
-| Domain            | IP Address    | Comment     |
-| :---------------- | :------------ | :---------- |
-| raspberrypi.local | 192.168.0.105 | raspberrypi |
-| homeoffice.local  | 192.168.0.108 | homeoffice  |
+| Domain           | IP Address    | Comment     |
+| :--------------- | :------------ | :---------- |
+| raspberrypi.home | 192.168.0.105 | raspberrypi |
+| homeoffice.home  | 192.168.0.108 | homeoffice  |
 
 ### CNAME records
 
-Local CNAME records map service domain names to their machine's domain name.
+`.home` CNAME records map service domain names to their machine's domain name.
 
-| Domain         | Target            |
-| :------------- | :---------------- |
-| jellyfin.local | raspberrypi.local |
-| notes.local    | raspberrypi.local |
+| Domain        | Target            |
+| :------------ | :---------------- |
+| jellyfin.home | raspberrypi.local |
+| notes.home    | raspberrypi.local |
 
 ## Groups
 
@@ -47,10 +50,48 @@ Emma
 - No adlist?
 - Whitelisted Google ad services anyway.
 
-## Debugging
+## Debugging DNS (from homeoffice)
+
+### Server health check
 
 Check Pi-hole's status:
 
 ```bash
+ssh raspberrypi
 pihole status
 ```
+
+### Client health check
+
+Confirm that the network interface controller is using the expected DNS server:
+
+```bash
+# List interfaces to find ethernet or wi-fi controller.
+nmcli | grep ": connected to"
+
+# Show the DNS servers used by the controller.
+nmcli device show <interface> | grep DNS
+```
+
+Restart the name resolution service:
+
+```bash
+sudo systemctl restart systemd-resolved
+```
+
+## How Linux machines choose a DNS server
+
+### When using DHCP
+
+DNS servers are determined by `/etc/dhcpcd.conf`:
+
+```bash
+# Get the DNS servers list from the DHCP server, which is usually on the router.
+option domain_name_servers
+
+# Or, set a list of DNS servers explicitly.
+# e.g.
+# - 1.1.1.1      Cloudflare
+# - 192.168.0.1  LAN Router
+static domain_name_servers=1.1.1.1,192.168.0.1
+```