Summary
This article focuses on Dynatrace Synthetic Monitoring, specifically Network Availability Monitors (NAM) using DNS, and explains why a private Synthetic location may not be selectable when creating DNS monitors.
It helps you understand the platform prerequisites and system‑level dependencies that determine whether DNS monitoring is available from a private location, and how to validate DNS availability using ActiveGate diagnostics and local DNS checks.
Problem
After deploying Synthetic‑enabled ActiveGates and assigning them to a new private Synthetic location, the location appears as Not supported when attempting to create a DNS Network Availability Monitor.
In the Dynatrace UI
You may observe one or more of the following:
- In Synthetic → Private locations, the private location shows a Compatibility health alert
- Network Availability (DNS) is missing from the available monitor types under
Classic Settings → Web and mobile monitoring → Private Synthetic locations → Edit location
- The private location is marked as Not supported, with a message indicating that the location is not configured to execute this type of monitor
Evidence in ActiveGate logs
The ActiveGate diagnostic logs (vuc-status.log) indicate that DNS is unavailable, even though other multi‑protocol capabilities may still be operational:
2026-06-09T07:29:46,227Z [DiagnosticResultsHolder]
multi-protocol = `DiagnosticResultsChangedEvent[moduleName=MULTIPROTOCOL, diagnosticCasesResult=DiagnosticCasesResult[isOperational=true, cases={MULTIPROTOCOL_TCP=DiagnosticCaseDetail[isAvailable=true], MULTIPROTOCOL_DNS=DiagnosticCaseDetail[isAvailable=false], MULTIPROTOCOL_ICMP=DiagnosticCaseDetail[isAvailable=true]}]]`
When MULTIPROTOCOL_DNS is reported as isAvailable=false, DNS NAM monitors are automatically disabled for the private location.
For information on finding the log see Useful Synthetic ActiveGate logs
Troubleshooting steps
Use the following steps to determine whether the limitation is related to Dynatrace configuration or to host‑level DNS resolution.
1. Review ActiveGate diagnostic results
On the ActiveGate host, check the vuc-status.log and confirm whether DNS is reported as unavailable:
MULTIPROTOCOL_DNS=DiagnosticCaseDetail[isAvailable=false]
If DNS is unavailable at this level, the private Synthetic location cannot support DNS NAM monitors.
2. Understand how DNS availability is validated
DNS Network Availability Monitors rely on the host operating system’s DNS resolver.
When applicable, entries defined in the /etc/hosts file are also used for hostname resolution.
Important characteristics:
- The ActiveGate uses the machine’s configured DNS settings
/etc/hosts is consulted when relevant hostnames are defined there- No Dynatrace‑specific DNS server is bundled with the ActiveGate
- If DNS resolution fails at the OS level, DNS execution is disabled automatically
This means that DNS availability for a private Synthetic location is determined entirely by the host’s ability to resolve hostnames, using standard operating system resolution mechanisms.
3. Verify local DNS resolution on the ActiveGate host
🔎 Use nslookup for basic DNS validation
Run the following command directly on the ActiveGate host:
nslookup -debug -type=A localhost
This check validates that:
- The local DNS resolver is reachable
- DNS queries are processed successfully
- The system can resolve hostnames using its configured DNS servers
If this command fails, DNS NAM monitors will not be enabled for the private Synthetic location.
🔎 Use dig for detailed DNS validation
In addition to basic DNS checks, you can use the dig command on the ActiveGate host to validate DNS resolution more precisely.
👉 Run a simple lookup:
👉 This allows you to:
- Verify that the domain resolves correctly from the ActiveGate host
- Confirm the returned IP address(es)
- Check response status (for example
NOERROR, NXDOMAIN, or timeout)
👉 For more targeted testing, you can:
dig <TARGET_DOMAIN> A
dig <TARGET_DOMAIN> @<DNS_SERVER_IP>
4. Check system‑level DNS configuration
Confirm that the ActiveGate host has:
- Valid DNS servers configured (for example, in
/etc/resolv.conf on Linux)
- No firewall or security tooling blocking DNS traffic
- No container or sandbox restrictions preventing access to the system resolver
Resolution
DNS availability in a private Synthetic location depends entirely on the underlying host’s ability to perform DNS resolution.
If DNS resolution is not functional at the system level:
MULTIPROTOCOL_DNS is marked as unavailable- The private Synthetic location is marked as Not supported for DNS monitoring
Once DNS resolution is restored on the host:
- The ActiveGate automatically reports DNS as available
- The private Synthetic location updates its compatibility status
- DNS NAM monitors become selectable without additional Dynatrace configuration
After resolving the cause of the failure
After DNS is reported as available:
- Verify that DNS appears as a supported capability for the private location
- Create a DNS Network Availability Monitor
- Confirm successful execution from the private Synthetic location
What’s next
If none of the previous steps resolved the issue, open a chat and provide the Support Archive from the ActiveGate with the troubleshooting steps you have already completed.
Related reading
📖 Manage Private locations
📖 NAM monitors in containerized locations
📖 Synthetic troubleshooting map
📖 Useful Synthetic ActiveGate logs
