There are no Selectel NS servers listed on the domain registrar side: a.ns.selectel.ru, b.ns.selectel.ru, c.ns.selectel.ru, d.ns.selectel.ruso resource records are given from the domain registrar's servers.
Checking zone delegation in status НЕ ДЕЛЕГИРОВАНА happens every 15 minutes
DELEGATED.
Managing domain resource records delegated to Selectel servers, resource records are transferred from Selectel servers