Welcome to WebmasterWorld Guest from 18.104.22.168
Mozilla/5.0 (compatible; YandexBot/3.0; +http://yandex.com/bots)
Yandex is robots.txt compliant.
The range above that is fairly deadly - 22.214.171.124/18
In fairness, Yandex's own docs stress that you should look at UA rather than IP.
All Yandex robots have names ending in “yandex.ru”, “yandex.net” or “yandex.com”. If the host's name has a different ending the robot does not belong to Yandex
There are many IP addresses that Yandex robots can originate from, and these IP addresses are subject to change. We are therefore unable to offer a list of IP addresses and we do not recommend using a filter based on IP addresses.
you can safely leave the rest to robots.txt.