Can't get when a hosting company offers Metered/Unmetered bandwidth in their dedicated servers plans. I mean AYKsolutions.com provides that.
How would you comment that?

Actually unmetered bandwidth means that you get a specific port for your server like we give 10mbps port unmetered bandwidth with our every server which is upgradeable to 100mbps port. Now this means is that your bandwidth is not measured on traffic but your server can always use 100mbps port.

In metered bandwidth like of 2000 gb or 3000 gb bandwidth is measured on your traffic, like if your server requires more connections than 10mbps port your server can automatically use it however in unmetered it can not.

So in unmetered bandwidth traffic is not measured but in metered bandwidth you have the advantage of using port speed whatever your server required by you will have to pay for any extra bandwidth usage in this way ..

Exactly, this is called "burstable" bandwidth. It good for having peaks where you need the full port speed, but bad if you use it all the time.
10 mbps unmetered is usually a good solution for most needs, as it equals about 3200 Gb.

I have seen also metered and unmetered servers from ExMasters.com. Are these the some notions?

It seems that exmasters.com in cace of the metered give you fixed pipeline and you pay for the each GB in case with unmetered you use the pap and pay only for that. I think that exmartes leave great choice for the ones who knows own bandwidth exactly.

If you use adult hosting (ExMasters.com specializes in it), it's much better to use unmetered dedis as this kind of web hosting services demands much bandwidth.

You need to know your traffic and only in this case you can decide on the metered or unmeterd trafic.

I believe you are right here. For those who proviode adult hosting unmetered dedis are more preferable.
I wonder how much does Exmasters.com dedis cost? Unmetered I mean for sure.

It depends on the port speed, for a 10MBPS unmetered - cost difference between a metered server can be $25-$125 in difference - but 100MBPS unmetered you're looking at an $1100 upgrade in most cases.