$TTL    24h
$ORIGIN 2.168.192.IN-ADDR.ARPA.
@       IN SOA ns.xai-corp.net. root.xai-corp.net. (
                20150920; serial
                3h      ; refresh
                1h      ; retry
                1w      ; expiry
                1d )    ; minimum

@               IN NS   ns.xai-corp.net.

1               IN PTR  gateway.xai-corp.net.
3               IN PTR  wireless.xai-corp.net.
13              IN PTR  printer.xai-corp.net.
14              IN PTR  laser.xai-corp.net.
16              IN PTR  tv.xai-corp.net.
103             IN PTR  xaicorp1.xai-corp.net.
12              IN PTR  home.xai-corp.net.