DNS Monitor www.google.com down but gmail.com up

Dear sir/madam, I had the DNS monitor

Interval    5
Up Interval 0
Time Until Up   0
Timeout 16
Manual Resume   0
query_name  www.google.com
accept_rcode    no-error
query_type  a
recv_i  
answer_contains query-type

It worked for long time but today it change to down. I change query_name to "gmail.com", it change to up. I test with nslookup

nslookup gmail.com 8.8.4.4
Server:         8.8.4.4
Address:        8.8.4.453

Non-authoritative answer:
Name:   gmail.com
Address: 216.58.197.101

nslookup www.google.com 8.8.4.4
Server:         8.8.4.4
Address:        8.8.4.453

Non-authoritative answer:
Name:   www.google.com
Address: 42.119.208.152
Name:   www.google.com
Address: 42.119.208.163
Name:   www.google.com
Address: 42.119.208.148
Name:   www.google.com
Address: 42.119.208.178
Name:   www.google.com
Address: 42.119.208.182
Name:   www.google.com
Address: 42.119.208.187
Name:   www.google.com
Address: 42.119.208.172
Name:   www.google.com
Address: 42.119.208.173
Name:   www.google.com
Address: 42.119.208.177
Name:   www.google.com
Address: 42.119.208.167
Name:   www.google.com
Address: 42.119.208.153
Name:   www.google.com
Address: 42.119.208.183
Name:   www.google.com
Address: 42.119.208.157
Name:   www.google.com
Address: 42.119.208.158
Name:   www.google.com
Address: 42.119.208.162
Name:   www.google.com
Address: 42.119.208.168

The difference is gmail.com returns 1 IP address, but www.google.com return alot. Why? And how to fix it? (if I want to monitor www.google.com) Thanks

Phong