wildcard and domain in /etc/resolv.conf

I have encountered a strange problem which ping, nslookup and curl commands some domains such as github.com returns a wildcard host (10.27.0.50 in this case) defined in BIND9 zone file if the /etc/resolv.conf is set to

domain home.ngs
nameserver 10.27.0.40
nameserver 10.27.0.50

and a BIND9 zone file with the following content:

;
; BIND data file for home.ngs
;
$ORIGIN home.ngs.
$TTL    7d  ; Time to live for a week
@   IN  SOA ns.home.ngs. hostmaster.home.ngs. (
            2024042400
            7d
            1d
            28d
            7d )
                IN      NS      ns.home.ngs.
                IN      NS      ns2.home.ngs.
        IN  A   10.27.0.50
                IN      TXT     "Ng's Home LAN"
;
; Addresses for the canonical names
;
@       IN  A   10.27.0.50
ns      IN  A   10.27.0.50
ns2     IN  A   10.27.0.40
nuc13           IN      A       10.27.0.50
;
; Aliases
;
*               IN      CNAME   nuc13

Not all domains are affected, just some. dig command is unaffected.

Is it caused by * mapped to multi-level subdomain? Is there a way to declare a single level wildcard?