How does an IS-IS router acknowledge the receipt of an IS-IS LSP on a point-to-point link?
They are explicitly acknowledged by sending a CSNP to the sender identifying the LSP.
They are implicitly acknowledged as a part of the link-state database synchronization and maintenance procedures.
They are explicitly acknowledged by sending a PSNP to the sender identifying the LSP.
They are implicitly acknowledged by the DIS multicast of CSNPs.
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