AI agents call passive_dns_for_domain to retrieve information from SeldomMaster without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Passive DNS lookups retrieve historical DNS resolution data for a given domain from threat intelligence APIs (likely GreyNoise, OpenCTI, or similar services mentioned in server description). This is a non-destructive, read-only query operation that gathers network intelligence. No data is created, modified, deleted, or financial transactions occur.
From the tool's definition Tool name 'passive_dns_for_domain' and the term 'passive' in DNS reconnaissance context indicates querying historical DNS records without executing active probes or modifying data. This aligns with threat intelligence data retrieval.
Documented attack patterns abuse exactly the kind of access passive_dns_for_domain gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and SeldomMaster, and nothing reaches the server without passing your rules. This is the rule we recommend for passive_dns_for_domain:
{
"version": "1",
"default": "deny",
"tools": {
"passive_dns_for_domain": {}
}
}passive_dns_for_domain is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Name: passive_dns_for_domain. It is categorised as a Read tool in the SeldomMaster MCP Server, which means it retrieves data without modifying state.
Register the SeldomMaster MCP server in PolicyLayer and add a rule for passive_dns_for_domain: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches SeldomMaster. Nothing to install.
passive_dns_for_domain is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the passive_dns_for_domain rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for passive_dns_for_domain. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
passive_dns_for_domain is provided by the SeldomMaster MCP server (paralax/seldommonster). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from SeldomMaster, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
52 SeldomMaster tools catalogued and risk-classified — across an index of 43,000+ MCP servers.