What happens at the network level when you open a browser and enter yandex.ru?

When you enter yandex.ru in a browser, several steps occur at the network level:

1. DNS query: the browser contacts the DNS server to obtain the IP address of the yandex.ru domain.
2. Establishing a TCP connection: after obtaining the IP, the browser establishes a TCP connection with the server on port 80 (HTTP) or 443 (HTTPS) through a three-way handshake (SYN, SYN-ACK, ACK).
3. TLS handshake (if HTTPS): a secure connection is established, certificates are exchanged, and cipher suites are negotiated.
4. Sending an HTTP request: the browser sends an HTTP GET request to the server.
5. Server response: the server processes the request and sends back an HTTP response with the page content.
6. Closing or maintaining the connection: depending on the settings, the connection may be closed or kept open for subsequent requests.

This entire process occurs at the level of TCP/IP and HTTP/HTTPS network protocols, ensuring data delivery from the client to the server and back.