Got redirected on normal link to site(s) with pornographic material

[kruso2]

For a short period of time all the users connected to the wifi in my home got redirected to different sites showing girls without clothes. Occurred on various links via Google but also when we tried to access sites directly. How is this possible? Is this caused by my internet provider? Router?

 

[kruso2]

The cause was DNS. I don't know how it had been changed to this spam address.