Do you have a question about SEO?

[Spike]

Is robots.txt necessary for a site?

It's depends if you have files that you don't want crawled by the Search Engine Spiders (Contact Us Page, etc). I don't personally use one on my sites.

[Zimbra.i2k2]

Thanks you very much to all and welcome your suggestion always I please with all the guys that can share your view about Mirror image and canonical issue

Again thanks
I2k2 Networks

[jialing]

Is robots.txt necessary for a site?

Robots.txt is important to tell search engine pages that not to crawl. For SEO purpose, we can use robots.txt to disable crawling to duplicate content.