While using a third-party DNS server can enhance your privacy, it will not completely stop your ISP (Internet Service Provider) from knowing what content you have downloaded. Here's a breakdown of why:
What a Third-Party DNS Does:
* Translates Domain Names: DNS (Domain Name System) is like the internet's phonebook. When you type a website address (like "example.com"), a DNS server translates that into the website's numerical IP address (like "192.168.1.1") so your computer can connect to it.
* Privacy Benefit: By using a third-party DNS server (like Cloudflare, Google Public DNS, or others), you prevent your ISP's DNS servers from logging which websites you visit. This can offer a degree of privacy for your browsing activity, as your ISP won't have a direct record of every website you request.
Why It Doesn't Hide Downloaded Content:
* Traffic Visibility: While a third-party DNS hides the name of the website you are connecting to during the initial lookup, once the connection is established, all the internet traffic, including downloads, still passes through your ISP's network infrastructure.
* Connection Information: Your ISP can see:
* The IP address you are connecting to: Even though they don't know the domain name from the DNS request, they can see you are communicating with a specific IP address. While they might not immediately know what content is hosted there, they can potentially infer it over time or through traffic analysis.
* The volume of data transferred: ISPs monitor the amount of data you upload and download. Large downloads are easily noticeable.
* The type of traffic: They can often identify the protocols being used (e.g., HTTP, HTTPS, FTP, BitTorrent).
* The ports used: Certain types of downloads use specific ports, which can give clues about the content.
* HTTPS Encryption: If the website you are downloading from uses HTTPS (the secure version of HTTP, indicated by a padlock icon in your browser), the content of your download is encrypted. This means your ISP cannot see the exact files you are downloading. However, they can still see:
* You are connected to a specific IP address.
* A large amount of data is being transferred.
* The connection is using HTTPS.
* The domain name is often revealed through the Server Name Indication (SNI) during the initial TLS handshake, although newer protocols like Encrypted Client Hello (ECH) aim to address this.
* Unencrypted Downloads: If you are downloading files over an unencrypted connection (HTTP or FTP), your ISP can potentially see the specific files being transferred.
* Legal and Regulatory Requirements: In many jurisdictions, ISPs are required to retain certain logs of internet activity for a specific period for legal and regulatory purposes.
In summary, using a third-party DNS primarily enhances the privacy of your website browsing history by preventing your ISP from directly logging the domain names you visit. However, it does not encrypt your overall internet traffic or hide the fact that you are downloading content, the amount of data involved, or the IP addresses you are connecting to.
To further enhance your privacy and hide your downloaded content from your ISP, you would typically need to use a Virtual Private Network (VPN). A VPN encrypts all your internet traffic and routes it through a server in a different location, making it much harder for your ISP to monitor your online activities, including downloads.