[AusNOG] Telstra authoritative DNS issue

[Philip Loenneker]

Hi all,

We have been having issues resolving DNS zones that are hosted by Telstra, which appears to be due to their authoritative name servers not responding to requests from multiple subnets we own. For example, www.afl.com.au<http://www.afl.com.au> can not resolve unless we use a DNS server outside our network, such as 8.8.8.8. Our DNS servers use root hints. Using other service provider connections appears to work ok.

The two DNS servers that appear to be authoritative for the domain are:
lon-mdn-dns-0.ngcdn.telstra.com
chw-mdn-dns-0.ngcdn.telstra.com

Attempting to perform a DNS lookup directly against either of them times out. Wireshark shows the request going out, but no response. We can ping both hosts, and in fact an nmap reveals that they are likely F5 load balancers.

Is anyone else experiencing similar issues? Could someone from Telstra contact me off-list to help us identify the cause?

Regards,
Philip Loenneker | Network Engineer | TasmaNet
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