https://support.google.com/a/answer/60764

nslookup -q=TXT _spf.google.com 8.8.8.8

nslookup -q=TXT _netblocks.google.com 8.8.8.8
nslookup -q=TXT _netblocks2.google.com 8.8.8.8
nslookup -q=TXT _netblocks3.google.com 8.8.8.8

35.190.247.0/24
64.233.160.0/19
66.102.0.0/20
66.249.80.0/20
72.14.192.0/18
74.125.0.0/16
108.177.8.0/21
173.194.0.0/16
209.85.128.0/17
216.58.192.0/19
216.239.32.0/19

172.217.0.0/19
172.217.32.0/20
172.217.128.0/19
172.217.160.0/20
172.217.192.0/19
108.177.96.0/19
35.191.0.0/16
130.211.0.0/22

2001:4860:4000::/36
2404:6800:4000::/36
2607:f8b0:4000::/36
2800:3f0:4000::/36
2a00:1450:4000::/36
2c0f:fb50:4000::/36