Why can't nslookup get a domain name by ip?

Question

Domain Name System

What can prevent tracert, ping and nslookup from getting a domain name?
Example:
nslookup 82.192.95.170 will return habr.ru
nslookup 178.248.236.28 (ulmart) will return "UnKnown could not find 178.248.236.28: Non-existent domain"
The same behavior was found in citilink.ru and vgd.ru.
The question arose when viewing windump logs, when for some sites in icmp requests a domain name was substituted, and for the above IP.
Came from different computers and under different providers. Tried clearing the dns cache. Tried to find the difference in icmp and dns requests in wireshark. I looked at the information on 2ip.ru.
Ideas are over.

Answer 1

Obviously - the reverse (PTR) zone is not registered