I meant you can EITHER use the numeric IP address anytime you need to address a device, OR add the IP addresses --> name translations into your /etc/hosts files in which case you will be able to refer to the hosts by their unqualified names in the absence of any DNS / mDNS (Avahi) service e.g.
Then I can just do
steeldriver@lap-t61p:~$ cat /etc/hosts
# added local hosts IPv4 lookups so I can accesss them without DNS or mDNS/Avahi
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
steeldriver@lap-t61p:~$ ping -q -c1 htpc-01
PING htpc-01 (192.168.1.65) 56(84) bytes of data.
--- htpc-01 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 7.459/7.459/7.459/0.000 ms