What DNS Does
- DNS (Domain Name System) works like the Internet’s phonebook.
- You type amazon.com in your browser; DNS responds with the site’s real numeric address (IP address) so your computer can connect.
Primary Weakness
- Classic DNS does not check whether a reply actually came from the right source.
- Because there’s no built-in ID check, an attacker can send a fake reply with a wrong IP address.
- Your computer often trusts the first reply it sees—real or fake.
Why That’s Dangerous
- Traffic Hijacking – You think you’re visiting your bank, but you’re quietly redirected to a look-alike site that steals passwords.
- Cache Poisoning – DNS servers store answers to speed things up. If a bad answer slips in, all users who ask that server get the fake address until the cache is cleared.
- Malware Delivery – Attackers can point common names (updates, ad servers, etc.) to malicious servers and spread infections quickly.
How We Mitigate It
| Fix | How It Helps | Notes |
|---|---|---|
| DNSSEC | Adds digital signatures to DNS replies so devices can verify authenticity. | Adoption is growing but not universal. |
| HTTPS / TLS | Even if DNS lies, browsers can spot mismatched security certificates and warn you. | Works only when sites use HTTPS correctly. |
| Trusted DNS Resolvers | Public resolvers (e.g., Cloudflare, Quad9) validate and filter responses. | You still rely on the resolver’s security; best when combined with DNSSEC. |
Key Takeaway
Traditional DNS is fast and convenient but trusts without verifying. Until protections like DNSSEC are everywhere, use secure connections (look for HTTPS), choose reputable DNS services, and keep your devices updated to reduce the risk of being silently redirected to fake sites.
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