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These three monitor types cover low-level network health checks: ICMP reachability, TCP port availability, and DNS record validation.

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Ping monitor

Ping monitors send ICMP packets to one or more hosts and evaluate the combined result.

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Configuration

FieldTypeDefaultNotes
hostsArray<{ type, host, timeout, count }>one empty host rowAt least one host required
pingEvalstring (JS function)built-in defaultOptional custom eval
Host fields:
FieldTypeDefaultNotes
typeIP4 | IP6 | DOMAINIP4Address type
hoststring—Required
timeoutnumber1000Timeout per ping attempt in ms
countnumber3Number of ICMP packets to send

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Default eval behavior

  • UP if all hosts respond (alive === true)
  • DOWN if any host is unreachable
  • Latency = average latency across all hosts
The built-in eval function: 
async function (arrayOfPings) {
    let latencyTotal = arrayOfPings.reduce((acc, ping) => {
        return acc + ping.latency;
    }, 0);

    let alive = arrayOfPings.reduce((acc, ping) => {
        return acc && ping.alive;
    }, true);

    return {
        status: alive ? 'UP' : 'DOWN',
        latency: latencyTotal / arrayOfPings.length,
    }
}

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Custom eval contract

Your function receives arrayOfPings and must return { status, latency }.

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Example

{
    "type": "PING",
    "type_data": {
        "hosts": [
            { "type": "IP4", "host": "8.8.8.8", "timeout": 1000, "count": 3 }
        ]
    }
}

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Troubleshooting

  • Frequent DOWN: some networks and firewalls block ICMP — consider switching to a TCP check on the same host
  • Noisy latency: increase count to reduce the effect of a single dropped packet
  • Validation error: the type field must match the format of the address (e.g., IP4 for IPv4 addresses)

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TCP monitor

TCP monitors attempt to open a connection to a host and port, and report whether the port is open, timeout, or error.

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Configuration

FieldTypeDefaultNotes
hostsArray<{ type, host, port, timeout }>one empty host rowAt least one host required
tcpEvalstring (JS function)built-in defaultOptional custom eval
Host fields:
FieldTypeDefaultNotes
typeIP4 | IP6 | DOMAINIP4Address type
hoststring—Required
portnumber80TCP port to probe
timeoutnumber1000Connection timeout in ms

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Default eval behavior

  • UP if every host result has status === "open"
  • DOWN otherwise
  • Latency = average connection latency across all hosts
The built-in eval function: 
async function (arrayOfPings) {
    let latencyTotal = arrayOfPings.reduce((acc, ping) => {
        return acc + ping.latency;
    }, 0);

    let alive = arrayOfPings.reduce((acc, ping) => {
        return acc && ping.status === "open";
    }, true);

    return {
        status: alive ? 'UP' : 'DOWN',
        latency: latencyTotal / arrayOfPings.length,
    }
}

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Custom eval contract

Your function receives arrayOfPings (TCP result objects) and must return { status, latency }.

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Example

{
    "type": "TCP",
    "type_data": {
        "hosts": [
            { "type": "IP4", "host": "db.example.com", "port": 5432, "timeout": 2000 }
        ]
    }
}

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Troubleshooting

  • Timeout: the network path is blocked or the service is slow to accept connections
  • Error: the host is wrong, the port is not listening, or DNS resolution failed
  • Validation error: the type field must match the format of the address

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DNS monitor

DNS monitors query a DNS record for a host and compare the returned values to your expected list.

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Configuration

FieldTypeDefaultNotes
hoststring—Required — the domain to query
nameServerstring""Optional DNS resolver override
lookupRecordstringARecord type to look up (e.g. A, AAAA, CNAME, MX, TXT)
matchTypeANY | ALLANYHow to compare results to expected values
valuesstring[][]Expected record values (at least one required)

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Match behavior

matchTypeResult
ANYUP when at least one expected value is present in the DNS response
ALLUP only when every expected value is present in the DNS response

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Value normalization

Before comparison, both the DNS response values and your expected values are normalized:
  • converted to lowercase
  • trailing . removed
  • whitespace trimmed

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Example

{
    "type": "DNS",
    "type_data": {
        "host": "example.com",
        "lookupRecord": "A",
        "matchType": "ANY",
        "values": ["93.184.216.34"]
    }
}

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Troubleshooting

  • Unexpected DOWN: copy the exact value from a manual dig query — normalization applies, so remove trailing dots
  • No response: verify that the record type exists and that the resolver is reachable from Kener
  • Partial mismatch with multiple IPs: use ANY for dynamic DNS setups where the response varies

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