I have a problem with DNS at one particular site.
My BT Business broadbands installed elsewhere (including on the same exchange) don't have a problem.
At this site 3-4 times a week DNS lookups start to fail, there's no apparent pattern to the failure times or network activity.
During the outage I can ping extenal DNSs but not BT's DNSs and nslookups to all DNS timeout.
The problem is rectified by rebooting the router (I'm using Draytek devices) but this is a business site so having to have the customer reboot the router several times a week is not acceptable.
Having the router configured to use BTs DNS or an extenall DNS (e.g. 220.127.116.11 or 18.104.22.168) makes no difference.
Anyone have any suggestions as to the problem?