buying premod modem from ebay, what other works are still required?

[earth890]

Hello all,

I am newbie. From reading some posts, looks like cert and mac are required, 
1. Does premod modem come with cert and mac? 
2. Is cert ISP-specific? if my ISP is spectrum, do i have to use spectrum cert? but some modems are supported by multiple ISPs. 
3. Will ISP accept two modems with same cert? what will happen?
4. Will ISP accept two modems with same MAC? what will happen? if i spoof mac, how do i know this MAC is not being used by other subscribers?

Please educate me.

[Wichin12]

1. Yes, they will have their original MAC and certs
2. No, certificates (certs) are for authentication purposes and they aren't specific for ISP's.
3. No, certs are attached to the MAC and they need to match, this is the same like using the same MAC in the same node.
4. No again, it's the same like in answer number 3, you need to read about MAC collide and why you can't use MAC clones in the same node.

[occalifornia]

Hello earth890,

1. Every DOCSIS 2/3 modem has certs and a mac.
2. by default, certs are unique to each device. the device you buy may have the original certs or the seller may copy one dump onto hundreds of modems. certs are not ISP specific.
3. If two modems go online with the same certs, the second one should be rejected.
4. same as 3.

Good luck with your testing. Be sure to get your ISPs permission!