Came across a peculiar issue.
TL;DR: Shaw DNS servers fail to resolve a shaw subdomaina used for webmail login.
I'm hoping a Shaw DNS engineer sees this; the guy I spoke to in the phone didn't seem to understand the problem.
- A client told me they couldn't access Shaw Webmail
- clicking the login button at www.webmail.shaw.ca does nothing. Plugging in a 3G stick makes it work.
- I changed the client DNS server to Google's (126.96.36.199) and that fixed it. I compared the DNS caches, and it ends up that wm.shaw.ca is failing to resolve when not on Google DNS.
- Our DNS server uses root hints, no explicit forwarder.
- If you trace the authority for wm.shaw.ca from the root hints, it goes:
- These 3 shaw servers can resolve all subdomains used in the webmail login process except wm.shaw.ca
Shaw, if these 3 servers are deprecated, you need to update the servers listed as authoritative for your domain. If they are active servers (they do respond to DNS queries), then they need to be able to resolve wm.shaw.ca. Please fix your infrastructure.
Service Engineer, Kerkhoff Technologies Inc.