How do I lower the load on a site with subdomains?
Yandex considers subdomains separate sites, so the robot crawls each subdomain. As a result, the load on the server may spike.
To reduce the number of robot requests, analyze the server log and determine where most of the requests come from. If they are from search engines and other robots, it's likely that the content of the main domain is sufficient for the visitors' needs. In this case, you may want to review the structure of subdomains and possibly stop using them or replace them with regional sections of the main site.
You can also configure the server to respond with the 429 HTTP status code. This response will indicate that the server experiences difficulties with the load. The Yandex robot will reduce the number of requests. Or you can change the site crawl rate yourself.