Have been looking in to this and it seems that Google's DNS servers are currently not returning CName results for any www. sub domain when you request an A Record from their DNS servers.
This only seems to affect www. sub domains, any other sub domain such as sub.example.com will return the CName record, it's only when you use www.example.com will they not return a CName record.
This is very odd behaviour and can only presume this maybe a miss configuration due to Google hardening their DNS servers to protect against DNS amplification attacks as their DNS servers are also not returning any additional information to queries.
We have adjusted our DNS zone for the time being to return a A Record for www.webwiz.net rather than a CName record.
Open and public DNS servers are increasingly being used for DNS amplification attacks where by an attacker sends a small packet with a spoofed IP from the network they are attacking to a DNS server which then sends back the response which is many time larger than the request. This then floods the target network with data bring it down.
Topic Options
Post Options
Thanks(0)
