protocol

DNS (Domain Name System)

DNS translates human-readable domain names like `example.com` into IP addresses that routers use to deliver network packets.

When a scraper requests `https://example.com`, the operating system's DNS resolver looks up the IP address associated with the domain by querying a recursive resolver, which in turn consults authoritative name servers. The result is cached for a period defined by the record's TTL (Time To Live). DNS resolution adds latency to the first request to each domain; subsequent requests use the cached IP.

For large-scale scraping, DNS can become a bottleneck or a detection surface. DNS-over-HTTPS (DoH) and DNS-over-TLS (DoT) encrypt resolver queries, preventing network-level DNS snooping. Some scraping proxy providers handle DNS resolution server-side so that the client's IP is never exposed in DNS traffic.

IP rotation via proxies means the scraper's DNS-resolved IP changes with each request or session. However, if the scraper and its proxy share the same DNS resolver, query patterns can reveal that many seemingly distinct IPs are controlled by the same entity.

Related Terms

A URL (Uniform Resource Locator) is the address of a resource on the web, comprising a scheme, host, optional port, path, query string, and fragment.

HTTP (HyperText Transfer Protocol) is the application-layer protocol used by web browsers and scrapers to request and receive resources from web servers.

A managed collection of proxy IP addresses used to distribute outbound requests across multiple origins and stay below per-IP rate limits.

Geolocation Targeting

Routing scraping requests through proxy IPs in a specific country or region to access geo-restricted content or localised pricing.

Content Delivery Network (CDN)

A distributed network of servers that delivers web content from locations geographically close to the user, often where anti-bot protection is deployed.

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DNS (Domain Name System) — Web Scraping Glossary | AlterLab