{"id":42098,"date":"2026-11-10T10:08:46","date_gmt":"2026-11-10T10:08:46","guid":{"rendered":"https:\/\/fastestvpn.com\/resources\/?p=42098"},"modified":"2026-11-10T10:09:15","modified_gmt":"2026-11-10T10:09:15","slug":"what-is-dns-cache","status":"publish","type":"post","link":"https:\/\/fastestvpn.com\/resources\/what-is-dns-cache\/","title":{"rendered":"What Is DNS Cache & DNS Cache Poisoning and How to Flush It","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

What is DNS cache? Have you heard of DNS cache poisoning? How do you flush DNS cache? This guide highlights answers to all your queries and ways to successfully execute them.\u00a0<\/span><\/p>\n

Your browser resolves a domain name in milliseconds, and you never notice. That speed depends on a small, temporary storage layer called the DNS cache.\u00a0<\/span><\/p>\n

However, that same layer becomes a target for one of the internet’s older attack techniques, and that is called DNS cache poisoning. This guide explains both concepts in plain technical terms, then shows you exactly how to flush the cache on any system.<\/span><\/p>\n

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What Is a DNS Cache?<\/h2>\n

A DNS cache is a temporary database that stores domain-to-IP mappings. It\u2019s so your system does not query authoritative servers every time you visit a website.\u00a0<\/span><\/p>\n

When a resolver receives a query, it checks the cache first. If a valid record exists, the resolver returns it immediately. If not, it performs the full lookup and stores the answer for future use.<\/span><\/p>\n

How Does Caching Happen?<\/h3>\n

It happens at two distinct layers.\u00a0<\/span><\/p>\n

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The client-side resolver cache sits on your operating system. Windows maintains it through the DNS Client service, and you can inspect it with <\/span>ipconfig \/displaydns<\/b>. This cache holds records your device recently queried.<\/span><\/p>\n

The recursive resolver cache sits on the DNS server your device points to, your ISP’s resolver, a public service like 1.1.1.1, or an internal corporate server.\u00a0<\/span><\/p>\n

This cache serves every client that queries that resolver, which makes it larger and far more consequential for security.<\/span><\/p>\n

How TTL Controls Cache Lifetime<\/h3>\n

Every DNS record carries a Time to Live (TTL) value in seconds.\u00a0<\/span><\/p>\n

The TTL tells the resolver how long it may keep the record before discarding it and performing a fresh lookup. A TTL of 300 means the record stays cached for five minutes, and a TTL of 86400 means it stays for a full day.<\/span><\/p>\n

Time to Live (TTL) creates a direct trade-off. Short TTLs propagate changes faster but generate more queries to authoritative servers. Long TTLs reduce load but slow down updates.\u00a0<\/span><\/p>\n

When you flush your DNS cache manually, you force the resolver to discard everything and start fresh.<\/span><\/p>\n

What Is DNS Cache Poisoning?<\/h2>\n

DNS cache poisoning, also called DNS spoofing, is an attack in which someone corrupts a resolver’s cache by injecting false DNS records.<\/span><\/p>\n

\u00a0The resolver then returns the attacker’s IP address instead of the legitimate one. It redirects users to malicious infrastructure such as phishing pages or attacker-controlled proxies.<\/span><\/p>\n

How Does a DNS Cache Poisoning Attack Work?<\/h3>\n

DNS queries typically travel over UDP, which has no handshake. Instead, the resolver validates a response by matching three values:\u00a0<\/span><\/p>\n