Local DNS not reliable

The problem isn’t limited to Windows.

It’s the same with Linux!

I installed a Linux Mint VM on a test PC with three network cards: two green and one blue.

I created three fixed leases in DHCP for each card, each with a different name.

/var/ipfire/dhcp/fixleases
00:0c:29:86:74:c9,192.168.20.11,on,,,,mintPC
00:0c:29:86:74:d3,192.168.20.20,on,,,,mintPC2
00:0c:29:86:74:dd,192.168.10.10,on,,,,mintPCBlue

I created the same addresses in hosts

/var/ipfire/main/hosts
on,192.168.20.11,mintPC,localdomain,on
on,192.168.20.20,mintPC2,localdomain,on
on,192.168.10.10,mintPCBlue,localdomain,on

I connected the three network cards alternately, disconnecting the previous one each time.

And here’s what I get in my Linux Mint terminal:

phili@linuxmint:~$ ssh -p 222 root@192.168.20.1 
root@192.168.20.1's password: 
Last login: Mon Apr 28 20:51:04 2025 from 192.168.20.20
[root@ipfireTest ~]# unbound-control list_local_data | grep linuxmint
10.10.168.192.in-addr.arpa.	60	IN	PTR	linuxmint.localdomain.
11.20.168.192.in-addr.arpa.	60	IN	PTR	linuxmint.localdomain.
20.20.168.192.in-addr.arpa.	60	IN	PTR	linuxmint.localdomain.
linuxmint.localdomain.	60	IN	A	192.168.10.10
linuxmint.localdomain.	60	IN	A	192.168.20.20
linuxmint.localdomain.	60	IN	A	192.168.20.11

[root@ipfireTest ~]# nslookup linuxmint 192.168.20.1
Server:		192.168.20.1
Address:	192.168.20.1#53

Name:	linuxmint.localdomain
Address: 192.168.10.10
Name:	linuxmint.localdomain
Address: 192.168.20.20
Name:	linuxmint.localdomain
Address: 192.168.20.11

[root@ipfireTest ~]# unbound-control list_local_data | grep 10.10
110.100.in-addr.arpa.	10800	IN	NS	localhost.
110.100.in-addr.arpa.	10800	IN	SOA	localhost. nobody.invalid. 1 3600 1200 604800 10800
10.10.168.192.in-addr.arpa.	60	IN	PTR	linuxmint.localdomain.
10.10.168.192.in-addr.arpa.	60	IN	PTR	mintPCBlue.localdomain.
linuxmint.localdomain.	60	IN	A	192.168.10.10
mintPCBlue.localdomain.	60	IN	A	192.168.10.10

[root@ipfireTest ~]# unbound-control list_local_data | grep 20.11
linuxmint.localdomain.	60	IN	A	192.168.20.11
mintPC.localdomain.	60	IN	A	192.168.20.11

[root@ipfireTest ~]# unbound-control list_local_data | grep 20.20
20.20.168.192.in-addr.arpa.	60	IN	PTR	linuxmint.localdomain.
20.20.168.192.in-addr.arpa.	60	IN	PTR	mintPC2.localdomain.
linuxmint.localdomain.	60	IN	A	192.168.20.20
mintPC2.localdomain.	60	IN	A	192.168.20.20

phili@linuxmint:~$ host linuxmint
linuxmint.localdomain has address 192.168.20.20
linuxmint.localdomain has address 192.168.20.11
linuxmint.localdomain has address 192.168.10.10