What makes a block to be rejected?

[unick]

Hi,

I am trying to figure out what makes a block being rejected... what are the possible reasons?  Are those reasons dependant on the type of currency or it's the same logic for any currency?  Is it hardware related? Is it network related?

thanks for your input!

[RChevalier]

I can only contribute my personal observation:

I find my rigs that are plugged in (ethernet) always seem to have lower rejections than the wirless rigs.  The wireless rigs are not in the best area for coverage, always hovers between 2-3 bars.  The rigs are exactly the same hardware wise, and I've tested it by starting them all at the same time as well.

[Satobit]

blocks? like the block found by the miners?

For bitcoin the most important thing is that the SHA256 hash of the block meet the mining difficulty criteria, e.g. with enough number of "0" at the beginning of the hash.

different crypto currency of course will has different criteria. But they could use the same criteria as bitcoin.

[unick]

blocks? like the block found by the miners?

For bitcoin the most important thing is that the SHA256 hash of the block meet the mining difficulty criteria, e.g. with enough number of "0" at the beginning of the hash.

different crypto currency of course will has different criteria. But they could use the same criteria as bitcoin.

yes like the block found by the miner... so if the rig finds a block and it's being rejected, could it be because the difficulty change while the rig was working on a previous block, so when it's being submitted it gets rejected because it doesn't meet the difficulty criteria anymore ?

Does this logic makes sense ?

[RChevalier]

I apologize.  I misread your question: blocks for shares.  Hope it didn't add to the confusion.

[J35st3r]

"Stale" shares are due to a block (a real one, not a share) being found on the network in the time between your miner starting a piece of work and submitting the share. They are pretty rare these days if you are mining with the statum protocol (the norm), but on the older getwork protocol it was a significant problem. Other possible reasons include hardware errors (wrong hash), but these are trapped by the mining software  (eg cgminer) so should not be submitted to the pool.

Then again, if you really meant block (as in solo mining), in this case you are mining at the network difficulty and bitcoind is acting like your private "pool", so a reject here will again be due to another block being found on the network, invalidating your work. Orphaned blocks are another matter, but you won't see these rejected by bitcoind, they just result in you missing out on your 25btc because the network decided that your block was in the shorter chain, sorry that's just how the protocol works, win some, lose some.