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Security Operations · Intermediate

DNS Sinkhole

A DNS server configuration that returns a controlled IP for known malicious domains to block and identify infected hosts.

Definition

When infected hosts query a sinkholed C2 or malware domain, they receive an internal address instead, preventing communication and revealing which hosts are compromised through sinkhole logs. Researchers also sinkhole botnet domains to disrupt them. Palo Alto firewalls include a DNS sinkhole feature.

Example

Infected hosts resolving a DGA domain to 10.255.255.1, where the SOC logs their connection attempts.

Exam tip

Sinkholing both blocks C2 and identifies infected internal hosts.

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