UseDNS determines whether IP Address to Hostname lookup and comparison is performed.
if you are connecting systems via ip address , or you have systems mapped to /etc/hosts file you can disable ssh dns look up to make ssh connections faster.
# echo “UseDNS no” /etc/ssh/sshd_config
UseDNS no /etc/ssh/sshd_config
H server.sand.box root ~ systemctl restart sshd