DNS reverse, PTR in logstash

Hello, I would like to obtain the host name as a string instead of the IP.(make a DNS reverse or PTR) Could it be possible?
This is my configuration filter>
mutate {
rename => ["@host", "host"]
}
dns {
reverse => [ "host" ]
action => [ "replace" ]
}
Where is the problem? my logs always appears with the IP.
Thank you
best regards

Solved!!
In CentOS machines logstash take the IPv6 address by default.
It is necesary to write the IPv4 DNS address in
nameserver => "XXX.XXX.XX.XX"