> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kraken.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Test Request

> Probe whether the counterparty is still alive

<div className="api-banner">
  <span className="api-protocol fix">FIX</span>
  <span className="api-detail">session: admin</span>
  <span className="api-tag">35=1</span>
</div>

Sent when nothing has arrived within the heartbeat interval and the session's liveness is in doubt. The counterparty must respond with a Heartbeat echoing TestReqID, which is how the probe is matched to its answer.

**Direction:** Either direction

***

<ResponseField name="header" type="" required>35=`1`</ResponseField>

<ResponseField name="112 - TestReqID" type="string" required>
  Token identifying the test request. A heartbeat answering a test request must echo the value it carried.
</ResponseField>

<ResponseField name="trailer" type="" required />