What Is a Resolver?
ResolverOverview of Resolver
When a user enters a web address into a browser, the request is sent to a DNS resolver to translate the human-readable domain name into a machine-readable IP address. The resolver can be a recursive resolver, which queries multiple authoritative nameservers on behalf of the client, or a stub resolver, which simply forwards the query to another DNS server. Common public resolvers include services provided by ISPs as well as third-party operators such as Google Public DNS, Cloudflare, and Quad9. By caching DNS responses, resolvers reduce lookup times for frequently accessed domains and help optimize network performance.
Why Resolvers Are Important
Resolvers are a critical component of internet functionality, bridging the gap between human-friendly domain names and the numerical IP addresses that computers use. Their performance and reliability directly affect how quickly users can access websites and applications. From a security perspective, resolvers can block access to known malicious domains, prevent phishing attacks, and enforce corporate browsing policies. However, compromised or malicious resolvers can manipulate DNS responses, redirecting users to fraudulent or harmful sites.
How IPinfo Handles Resolver Data
IPinfo's datasets can provide valuable intelligence about IP addresses that operate as resolvers. We also provide a resolver tag. Reverse DNS lookups, ASN data, and hosting detection can reveal whether an IP belongs to a well-known DNS provider, an ISP-operated resolver, or a potentially suspicious network. This context is useful for security investigations, content delivery optimization, and understanding the infrastructure behind user traffic. By correlating resolver IPs with other metadata — such as geolocation, privacy flags, and network type — IPinfo enables a richer analysis of DNS resolution patterns.