Should I use a robot.txt or robot meta tags or both to ban indexing of certian pages.
I agree with Brett, go with what is easiest to maintain. If you have many web pages on your site and the web pages have been organized in file directories, it may be easier to use robots.txt.
On a side note, if you choose to use both ways, and there is a conflict between the directive in robots.txt and the meta tag directive (e.g. if your robots.txt allows spidering but your page meta tag does not) the robots.txt directive has precedence.