I am having problems accessing my website from time to time. Some subdomains are stopping to resolve or the main domain. It usually happens for 1 hour or 2, then I can access them (sometimes I am forced to use free web proxies to access my domain). I am hosting the domain on 2 nameservers using ISPConfig here is the list: service bind9 status: Code: Nov 12 16:58:01 admin.domain.com named[1309]: automatic empty zone: B.E.F.IP6.ARPA Nov 12 16:58:01 admin.domain.com named[1309]: automatic empty zone: 8.B.D.0.1.0.0.2.IP6.ARPA Nov 12 16:58:01 admin.domain.com named[1309]: reloading configuration succeeded Nov 12 16:58:01 admin.domain.com named[1309]: reloading zones succeeded Nov 12 16:58:01 admin.domain.com systemd[1]: Reloaded BIND Domain Name Server. Nov 12 16:58:01 admin.domain.com rndc[2129]: server reload successful Nov 12 16:58:01 admin.domain.com named[1309]: zone domain.com/IN: 'domain.com' found SPF/TXT record but no SPF/SPF record found, add matching type SPF record Nov 12 16:58:01 admin.domain.com named[1309]: zone domain.com/IN: loaded serial 2016111205 Nov 12 16:58:01 admin.domain.com named[1309]: zone domain.com/IN: sending notifies (serial 2016111205) Nov 12 16:58:01 admin.domain.com named[1309]: all zones loaded Nov 12 16:58:01 admin.domain.com named[1309]: running For example at the moment I can enter admin.domain.com (ISPConfig main interface) but I cannot access www.domain.com . When I enter in /etc/bind/ all hosts are working there is no .err domain . I am using Debian 8 & Ubuntu 16 on the servers. 1 of the IP's hosts ns1, main website, ISPConfig interface and the mail server(2 machines, 1 for NS1, admin, mainweb and 1 only for mail), ns2 has it own IP on a virtual machine.
from a different computer, ping the domain and check if it resolves to the correct ip address. If so, then it's a webserver setting. Then you need to check if you have enabled the www subdomain as well.
if it's for an hour or two at a time, and your 'A' records ttl's are 3600, id say one of your dns servers isn't getting the new info, and your pc is occasionally getting the dns response from the server with the wrong info. do a whois on the domain and check that the registered dns servers are the right ones. then run a dig for the domain against both registered dns servers to find out which one has the wrong data. just because you've resolved admin.domain.com from one dns server, doesn't mean that same dns server is the one that responds when you ask to www.domain.com straight afterwards. once you know where the problem is you can start looking at the configs to find the cause.
