I am getting some strange DNS/Network issues accessing sites running on my Ubuntu 10.10 instance on EC2. I have 6 sites VHosted on a single LAMP stack which have been quite happily working for a month or so and I have had no issues until now when I am trying to work on these sites from inside a new network at a friends house because my ISP is down. I didn't change anything and suddenly I cannot access my sites over HTTP from my Mac although my phone over 3G picks up the DNS fine so it looks like it's a property of the network I am on and externally all is working ok.
I have these 2 domains (plus 4 others) all mapped to the same Apache instance with a VHost set up for each domain:
- www.electrichummingbird.com
- www.comparetheotter.com
I have a default VHost that I can see is working from here so I know Apache and the instance are up:
http://ec2-46-137-25-238.eu-west-1.compute.amazonaws.com
Yet when I do access any of my domains (in 3 browsers, caches cleared) they just time out and when I do an nslookup from my local machine on www.comparetheotter.com (or any of the others) I get
;; connection timed out; no servers could be reached
Just to check off the obvious (to me) responses:
- I can SSH into my box and have tried restarting Apache
- I am only using CNAMEs, no A records in my DNS
- I did not change any DNS, EC2 or LAMP settings at all prior to noticing this issue
- All other websites work fine which is why I think this a property of my EC2 hosted sites
- I do not have any local DNS mod services running (XAMPP is shut down) and I've restarted my Mac
If anyone can help me understand what I am doing wrong it would be hugely appreciated. Many Thanks!
EDIT - Thanks @user48838 & @ccame, both very useful responses. I can now see it's a DNS issue but EC2 compounds matters as Amazon are regularly updating their DNS, perhaps even more so than usual due to the issues @user48838 mentions.
nslookup gives interesting findings - only certain external networks are able to find my server:
1.) - local - OK
nslookup www.kodental.co.uk
Server: 192.168.1.254
Address: 192.168.1.254#53 Non-authoritative answer:
www.kodental.co.uk canonical name = ec2-46-137-25-238.eu-west-1.compute.amazonaws.com.
Name: ec2-46-137-25-238.eu-west-1.compute.amazonaws.com
Address: 46.137.25.238
2.) - Other remote network - FAIL
nslookup www.kodental.co.uk 4.2.2.1
Server: 4.2.2.1
Address: 4.2.2.1#53** server can't find www.kodental.co.uk: NXDOMAIN
3.) - Google as suggested - OK
nslookup www.kodental.co.uk 8.8.8.8 Server: 8.8.8.8
Address: 8.8.8.8#53
Non-authoritative answer:
www.kodental.co.uk canonical name = ec2-46-137-25-238.eu-west-1.compute.amazonaws.com.
Name: ec2-46-137-25-238.eu-west-1.compute.amazonaws.com
Address: 46.137.25.238
That solves what the problem is although not how to fix it. Any suggestions as to what I (and others) can do to fix this would be most gratefully received :)
N.B Also - I am using FastHosts in the UK to provide my DNS. I log in and modify the settings for A & MX records etc via a web admin interface but I can't modify the TTL of my DNS