Any1 please explain me about boss resist ???

Bosses's status said "elemental and chaos resist " .I wonder if they resist all elemental damage or 75% maximum resistance ??? So if I use burning arrow will I cause fire damage and will the boss be ignited with the reduced damage amount affected by elemental resistance ?? I'm new and I'm planning on burning arrow build. This question make me concern alot @@ i know wow dame work on creep really well but I'm not sure how they work on bosses.
In conclusion will the boss take wow dame and "will they be ignite "?? If they can't be ignite can u advice me a highest puts dame build pls =)
Thank in advance

Wow is elemental and puts is physical ( wrong typing )

There is no immunity so enemies with resists will take reduced damage but they will take damage. You can counter resists by <elemental type> "penetration" and/or by <elemental type> "minus resistance". For elemental builds these can be very important.

http://pathofexile.gamepedia.com/Resistance

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Jojas wrote:

There is no immunity so enemies with resists will take reduced damage but they will take damage. You can counter resists by <elemental type> "penetration" and/or by <elemental type> "minus resistance". For elemental builds these can be very important.

http://pathofexile.gamepedia.com/Resistance

So will bosses be ignite ???

Sure. Look here: http://pathofexile.gamepedia.com/Ignite

But is it still only 30% resist in each element on merciless on bosses?
Same with Atziri?

You can easily check for resistances by applying a curse to mobs. When "resistant to" turns into "vulnerable to" on the mouseover, you will know the right amount, however you have to take into account the reduced curse effectiveness of bosses. See the wiki, it has all the answers :)