The detection rule 'Detect Long DNS TXT Record Response' is designed to identify suspicious activities related to DNS tunneling. Specifically, it focuses on DNS responses of type TXT that are excessively long, indicating possible data exfiltration, Command and Control (C2) communication, or attempts to evade security measures. By analyzing the length of responses to DNS TXT queries, the rule helps uncover anomalous DNS traffic patterns typically associated with malicious activities. However, this rule is marked as deprecated due to a shift in focus towards monitoring DNS queries rather than relying solely on DNS responses. Users should be aware of potential false positives from legitimate long TXT responses and can adjust the threshold to minimize these occurrences.