Explain DNS feature in README

README.md

@@ -36,8 +36,13 @@ sudo ip route add 0.0.0.0/1 dev tun0
 Note that if you paste these commands into a shell script, which you then run with `sudo`, you might want to replace
 `$USER` with `$SUDO_USER`.
 
-For DNS to work, you might need an additional tool like [dnsproxy](https://github.com/AdguardTeam/dnsproxy) that is
-configured to listen on a local UDP port and communicates with the upstream DNS server via TCP.
+This tool implements a virtual DNS feature that is used by default. When a DNS packet to port 53 is detected, an IP
+address from `198.18.0.0/15` is chosen and mapped to the query name. Connections destined for an IP address from that
+range will supply the proxy with the mapped query name instead of the IP address. Since many proxies do not support UDP,
+this enables an out-of-the-box experience in most cases, without relying on third-party resolvers or applications.
+Depending on your use case, you may want to disable this feature using `--dns none`.
+In that case, you might need an additional tool like [dnsproxy](https://github.com/AdguardTeam/dnsproxy) that is
+configured to listen on a local UDP port and communicates with a third-party upstream DNS server via TCP.
 
 When you terminate this program and want to eliminate the impact caused by the above several commands,
 you can execute the following command. The routes will be automatically deleted with the tunnel device.
@@ -52,15 +57,17 @@ Tunnel interface to proxy.
 Usage: tun2proxy [OPTIONS] --proxy <URL>
 
 Options:
-  -t, --tun <name>   Name of the tun interface [default: tun0]
-  -p, --proxy <URL>  The proxy URL in the form proto://[username[:password]@]host:port
-  -h, --help         Print help
-  -V, --version      Print version
+  -t, --tun <name>    Name of the tun interface [default: tun0]
+  -p, --proxy <URL>   Proxy URL in the form proto://[username[:password]@]host:port
+  -d, --dns <method>  DNS handling [default: virtual] [possible values: virtual, none]
+  -h, --help          Print help
+  -V, --version       Print version
 ```
 Currently, tun2proxy supports two proxy protocols: HTTP and SOCKS5. A proxy is supplied to the `--proxy` argument in the
 URL format. For example, an HTTP proxy at `1.2.3.4:3128` with a username of `john.doe` and a password of `secret` is
 supplied as `--proxy http://john.doe:[email protected]:3128`. This works analogously to curl's `--proxy` argument.
 
 ## TODO
+- Increase error robustness (reduce `unwrap` and `expect` usage)
 - UDP support for SOCKS
-- Virtual DNS
+- Native support for proxying DNS over TCP or TLS