swcbc Posted September 14, 2016 Share Posted September 14, 2016 DNS entry appears to not be registered anymore Using Google DNS it returns this. $ nslookup > server 8.8.8.8 Default server: 8.8.8.8 Address: 8.8.8.8#53 > service.hornbill.com Server: 8.8.8.8 Address: 8.8.8.8#53 Non-authoritative answer: *** Can't find service.hornbill.com: No answer Link to comment Share on other sites More sharing options...
swcbc Posted September 14, 2016 Author Share Posted September 14, 2016 ... and, it's back Link to comment Share on other sites More sharing options...
jeffreysmith Posted September 14, 2016 Share Posted September 14, 2016 Hi swcbc, We switched our DNS provider last night over to cloudflare and it appears this record was missed. I have added the record and it now appears in googles dns. C:\Users\jeffrey>nslookup Default Server: google-public-dns-a.google.com Address: 8.8.8.8 > service.hornbill.com Server: google-public-dns-a.google.com Address: 8.8.8.8 Non-authoritative answer: Name: service.hornbill.com Address: 78.129.173.117 Looks like I'm going to spend the morning making sure we have proper monitoring of all our service endpoints. Thanks for pointing this out so we could fix it. Link to comment Share on other sites More sharing options...
JonNutt Posted September 14, 2016 Share Posted September 14, 2016 Thanks this saved a lot of painstaking log analysis on my side to find why it wasn't working. Jon. Link to comment Share on other sites More sharing options...
Everton1878 Posted September 14, 2016 Share Posted September 14, 2016 That might explain why it is being quite intermittent for me today The Live and Admin sites are fine but the Service one has been working for some people but not others I tried some machines this morning and they could access but I've just tried them again and the page wasn't being found Link to comment Share on other sites More sharing options...
Gerry Posted September 14, 2016 Share Posted September 14, 2016 Because there was a DNS configuration problem it may be the TTL on some local or downstream DNS's are still caching the incorrect IP address. It should self resolve as those cached DNS records expire Gerry Link to comment Share on other sites More sharing options...
Keith Stevenson Posted September 14, 2016 Share Posted September 14, 2016 All, Following on from the above posts and as clarification. We monitor all service endpoints but have been monitoring them via their IP addresses and not using their FQDN (domain name), we also monitor our DNS service provider and to now that has worked ok. We made a decision to transition over to CloudFlare to take advantage of their superior service as well as future global caching to help accelerate our application content, this was executed last night. Unfortunately we misconfigured the DNS entry for service.hornbill.com but our monitoring continued to show the service as available because we were monitoring the service via its IP address and not its FQDN. We have now reviewed our monitoring setup and re-configured to use the domain name rather than IP address for all services to ensure this gap in our monitoring does not happen in the future. Sorry for any inconvenience caused. Kind Regards Keith Stevenson 1 Link to comment Share on other sites More sharing options...
swcbc Posted September 15, 2016 Author Share Posted September 15, 2016 On a related and frustrating note, this caused us to have to reconfigure firewall rules and whilst doing so discovered that live.hornbill.com has changed it's IP, no biggie as we can use a DNS for that, but the sender of email messages doesn't fit within that DNS quite right. If I do a DNS lookup for live.hornbill.com it returns a single IP address. Non-authoritative answer: Name: live.hornbill.com Address: 78.129.173.117 When I look for mail coming into our mail server it doesn't come from live.hornbill.com it comes from 87.117.243.10 Doing a reverse lookup on this Non-authoritative answer: 10.243.117.87.in-addr.arpa name = live.hornbill.com. Which is a bit messy in the firewall config as we have two entries for live.hornbill.com that are different. I think I understand why it's like that, to satisfy email RDNS, but it spannered me a bit yesterday as changing them to suit these DNS changes caused me to break email for a bit. At least until I figured this out. Link to comment Share on other sites More sharing options...
Everton1878 Posted September 19, 2016 Share Posted September 19, 2016 Is anyone still having problems with service.hornbill.com? Some of our machines can access it fine but others come up with 'This page can't be displayed' I can ping 78.129.173.117 and do tracert but I can't if I use service.hornbill.com We can access live.hornbill.com and admin.hornbill.com from the machines that can't access service.hornbill.com though Link to comment Share on other sites More sharing options...
Keith Stevenson Posted September 19, 2016 Share Posted September 19, 2016 Everton1878 Sorry to hear that your having trouble. There should be no issue as the DNS record for the above was fully propagated last week and the TTL on any old record should have passed easily by now. Can you do a NSLOOKLUP for service.hornbill.com from the CMD prompt on an effected machine and post the results as this will show us what DNS server your using, the records TTL etc. If you can also confirm this happens in all browsers that would help (Chrome does its own caching of DNS) Kind regards Link to comment Share on other sites More sharing options...
Everton1878 Posted September 19, 2016 Share Posted September 19, 2016 Hi @Keith Stevenson, we've found the issue Out infrastructure team had tried to set up a DNS entry to use a shorter name, decided it wasn't going to work but hadn't removed the configuration from DNS It was looking like it might've been DNS but it was strange how it worked from some machines and not others Thanks for coming back to me Link to comment Share on other sites More sharing options...
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