AI agents call dns.lookup to retrieve information from Mcp without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
DNS lookups are informational queries that retrieve publicly available DNS records (A, AAAA, MX, TXT, etc.). This is a classic Read operation with no capability to modify data, execute commands, or trigger external operations. The low severity reflects minimal blast radius—an agent misusing this tool could only enumerate DNS information, which is already public and carries negligible risk.
From the tool's definition Tool performs DNS record lookups via public DNS-over-HTTPS resolvers. DNS lookups are read-only queries that retrieve existing domain name system information without modifying, executing code, or causing side effects.
Attacks that exploit this kind of access
DNS records via public DNS-over-HTTPS resolvers. It is categorised as a Read tool in the Mcp MCP Server, which means it retrieves data without modifying state.
Register the MCP server in PolicyLayer and add a rule for dns.lookup: 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 Mcp. Nothing to install.
dns.lookup 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 dns.lookup 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 dns.lookup. 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.
dns.lookup is provided by the MCP server (@2sio/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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