Is there any linux DNS server software the will block certain sites at a particular time of day?
I think what you are looking is a proxy software that will allow you to deny/allow http requests. Squid, should work for you. Please note this isn't exactly trivial using setting up the config file. However, I did find a post that might be relevant to your specific problem.
As Hennes eludes to, DNS only services name resolutions (transforms www.google.com to 220.127.116.11).
DNS can not block access. It can refuse to resolve or return a different host.
Both of those might not work as expected if the client caches DNS information.
Example: You have a site which should only resolve between 9AM and 5PM
- Client tries to go to the site at a minute before 5PM, this works.
- Client reload the site 10 minutes later (now after the 5PM deadline)... it will still works.
An other example:
- Client tries to access the site at 8AM and gets the redirected to a different host.
- Client tries again after 9AM. The information is still cached and the client gets redirected again.
I am not sure what goal you want to achieve, but if you want to block sites from a coorperate network you might want to look at proxy software.