Error using yum

I tried updating my system using yum but in less than 2 seconds I get
numerous errors saying 'temporary failure in name resolution'. Is this
entirely my DNS server's fault or can there be any other reason behind
this. I suppose not but I would just like to confirm.

The sqlite.bz2 packages that yum tries to retrieve, are easily
accessible/downloadable through the web browser. When installing a
package, it again gives me the error and finishes with "No Mirrors to
try"  message.

But if I try to access the same rpm package repository through the
browser and I can easily do that. I can download the rpm through my
browser.

Shouldn't the DNS server block my request even through the browser?