segregated witness – How Does A Node Get Infomation From The TxID – that’s, is not the TxID the SHA^2(256) of varied transaction elements?

Sure, all TXIDs are solely calculated from non-witness information. Whereas many nodes have a whole copy of the blockchain, which does comprise all transactions, most nodes don’t have a full transaction index.

^{through https://developer.bitcoin.org/reference/p2p_networking.html}

Nodes will promote unconfirmed transactions. These are then obtainable to be shared upon a getdata tx request which might be responded to with a tx message.

If the transaction is already confirmed, the peer ought to know during which block the transaction was included (from the context during which it heard concerning the transaction within the first place), and would both request the entire block, or a Merkle department within the type of a merkleblock message.

You’ll be able to learn extra concerning the P2P messages for instance right here: https://developer.bitcoin.org/reference/p2p_networking.html