Our customers make quite a few domain checks towards Google public DNS with the following domains
<userid>.sip.teltel.io, but they often fail. To others, like Cloudflare it is always successful.
When we run nslookup in a loop towards 126.96.36.199, about 80% of the time Google fails to resolve. To 188.8.131.52 it is always successful. See below a failed example:
while : do nslookup 7157599388.sip.teltel.io 184.108.40.206 done
Server: 220.127.116.11 Address: 18.104.22.168#53 ** server can't find 7157599388.sip.teltel.io: NXDOMAIN
Thank you in advance!