The UseDNS option causes the OpenSSH daemon to perform a lookup of the remote hostname (via getnameinfo() and/or getaddrinfo()) in certain appropriate circumstances. Although this is typically a DNS lookup, these routines could be using a different name service such as /etc/hosts or NIS/NIS+. In such cases, the name of the option is misleading. Moreover, there are some diagnostics within canohost.c which assume that getnameinfo() is using DNS (e.g., "Nasty PTR record...")
The name of this option won't be changing
Mass change of RESOLVED bugs to CLOSED