fault DNS servers ?

[Vu Pham]

When I am at home, I often use my company DNS servers with my vpn 
connection. Today, when I accidentally had no vpn connection, I found 
that the dns servers that my ISP gave me always return  some IP address 
for any non-existent dns name.

The DNS servers I got are : 209.55.5.10 (ns1.broadbandsupport.net) and 
209.55.5.11 (ns2.broadbandsupport.net). See my test:

 > set type=a
 > server 209.55.5.10
Default server: 209.55.5.10
Address: 209.55.5.10#53
 > bad1.bad2.com
Server:         209.55.5.10
Address:        209.55.5.10#53

Non-authoritative answer:
Name:   bad1.bad2.com
Address: 72.4.162.130
Name:   bad1.bad2.com
Address: 207.189.119.29
 > abc.conm.com
Server:         209.55.5.10
Address:        209.55.5.10#53

Non-authoritative answer:
Name:   abc.conm.com
Address: 82.98.86.161
 > 123.456.78
Server:         209.55.5.10
Address:        209.55.5.10#53

Non-authoritative answer:
Name:   123.456.78
Address: 204.13.161.92
 > badq.bbb.com
Server:         209.55.5.10
Address:        209.55.5.10#53

Non-authoritative answer:
Name:   badq.bbb.com
Address: 204.13.161.92
 > wtf.wtf.wtf
Server:         209.55.5.10
Address:        209.55.5.10#53

Non-authoritative answer:
Name:   wtf.wtf.wtf
Address: 204.13.161.92
 > insane.dns.server
Server:         209.55.5.10
Address:        209.55.5.10#53

Non-authoritative answer:
Name:   insane.dns.server
Address: 204.13.161.92
 >


Is this just some wrong configuration or is it a result of some hacking ?

Vu