I was trying to use 2 methods "HOWTOMD5SUM" and "HOWTOSHA256SUM", but they are all way complicated for a newbie. Is there an application that could do the same in a simple way? I've already tried "checksum calculator" too, but it seems to work on iso files, not on live CDs.
How about choosing the "Check CD for defects" from the boot menu? :)
This is an screenshot from an old Ubuntu version, in newer versions you have to hit Enter during the boot process when you see this screen to see this menu:
md5 checking is not only used to check for errors, but to check for authenticity. You could have a cd that does not have errors, but that is non-authentic... ie., a hacked copy. It could also be a case that your download did not complete properly. It is possible to use the md5sum to ensure that what you are burning is valid and a complete copy. If you had an .iso that was not valid you could end up with a CD that would not boot (depends on where the error was in the downloaded file).
To check the md5sum of the .iso file you would:
You then take the result - 6cac02eb0b97633d3db3c86f1cf9a117 and compare it to themd5sum listed on the download page.
You can see that the md5sum is not the same as the one I generated. These are from daily builds so this is to be expected.