Monitoring DNS traffic can serve as an indicator of compromise (IOC) in network security, especially in detecting data exfiltration via DNS tunnels, a method often used by malware to bypass corporate firewalls. By utilizing Packetbeat, an open-source packet analyzer, DNS requests and responses can be indexed into Elasticsearch, allowing for the analysis and aggregation of data. The setup involves configuring Packetbeat to observe DNS traffic and using Watcher, part of Elastic's X-Pack, to generate alerts based on specific conditions, such as a high number of unique hostnames associated with a domain, which may indicate a DNS tunnel. The process includes setting up triggers and conditions for alerts, which are executed through actions like sending emails or logging messages when suspicious activity is detected. Tuning involves adjusting variables such as the time window and hostname threshold to balance sensitivity and minimize false positives. This approach underscores the importance of a layered defense strategy to enhance network security.