DNS over TLS (DoT) is a network security protocol designed to enhance the privacy and security of your internet activity by encrypting DNS traffic.
Based on the provided reference, DNS over TLS (DoT) is a network security protocol for encrypting and wrapping Domain Name System (DNS) queries and answers via the Transport Layer Security (TLS) protocol. In simpler terms, it adds a layer of encryption to the communication between your device and the DNS server you use.
Understanding DoT
Traditionally, DNS queries (the requests your computer sends to translate website names like www.example.com into IP addresses) were sent unencrypted over UDP or TCP port 53. This unencrypted traffic could be easily intercepted and read by anyone on the network path, including your ISP or malicious actors. This vulnerability allows for:
- Eavesdropping: Others can see which websites you are visiting.
- Tampering: DNS responses could be modified (e.g., redirecting you to a fake website in a phishing attack).
DoT addresses these issues by using Transport Layer Security (TLS), the same encryption protocol that secures HTTPS connections for websites.
How DoT Works
When you use DoT:
- Your device initiates a connection to a DoT-supported DNS server, typically over TCP port 853.
- This connection is then secured using TLS, creating an encrypted tunnel.
- All subsequent DNS queries and responses within that session are sent through this encrypted tunnel.
This encryption ensures that observers between your device and the DNS server cannot see the content of your DNS requests or the responses you receive.
Why is DoT Important?
The primary benefits of using DoT include:
- Enhanced Privacy: Prevents third parties, such as ISPs, from easily monitoring your internet activity based on your DNS queries.
- Increased Security: Protects against DNS spoofing and other forms of tampering with DNS data.
- Improved Trust: Verifies the authenticity of the DNS server you are communicating with through TLS certificates.
DoT vs. Other DNS Protocols
While DoT focuses on encrypting DNS traffic at the transport layer using TLS, it's helpful to compare it to standard DNS and another modern alternative:
| Feature | Standard DNS (UDP/53) | DNS over TLS (DoT) (TCP/853) | DNS over HTTPS (DoH) (TCP/443) |
|---|---|---|---|
| Encryption | No | Yes (using TLS) | Yes (using HTTPS/TLS) |
| Port Used | UDP/53 (primarily) | TCP/853 | TCP/443 |
| Traffic Type | Dedicated DNS channel | Dedicated DNS channel (TLS wrapped) | Looks like regular web traffic |
| Visibility | Clearly identifiable as DNS | Clearly identifiable as DoT (Port 853) | Blends in with other HTTPS traffic |
| Complexity | Simple | Moderately complex (TLS handshake) | Moderately complex (HTTPS overhead) |
Note: Both DoT and DoH provide significant privacy and security improvements over standard unencrypted DNS. DoT operates on a dedicated port, making it easier for network administrators to identify and potentially manage DNS traffic separately. DoH, by using port 443, makes DNS traffic harder to distinguish from regular web browsing, which can be desirable for users seeking maximum privacy but challenging for network filtering.
Practical Use and Examples
DoT support is becoming more widespread:
- Many public DNS providers (like Cloudflare, Google Public DNS) offer DoT endpoints.
- Major operating systems (like Android, iOS, Windows, macOS, Linux) are increasingly adding native support for configuring and using DoT.
- Some routers and network devices also allow configuring DoT for all devices on the network.
For example, on recent Android versions, you can often configure a "Private DNS" setting using a hostname (like one.one.one.one for Cloudflare) which will automatically attempt to use DoT.
By encrypting your DNS queries, DoT is a crucial step in making your online activities more private and secure from observation and manipulation on the network path.
