On an OSPF network, if a router receives an update of an LSA that exists in the local LSDB, the router updates the LSDB and floods the LSA.

Question

Options

• ATRUE
• BFALSE
• C
• D

• A
  16% (5)
• B
  74% (23)
• C
  6% (2)
• D
  3% (1)

Explanation

B is correct because OSPF doesn't blindly update and flood every received LSA - it first compares the received LSA's sequence number against the one already in the Link State Database (LSDB). Only if the received LSA is newer (higher sequence number) does the router update the LSDB and flood it; if the received LSA is the same age, the router simply acknowledges it without flooding; if it is older, the router discards it and re-floods the newer version back toward the sender.

A is wrong because the statement is unconditionally true, ignoring this critical sequence-number comparison - OSPF is more selective than a simple "always update and flood" rule.

Memory tip: Think of OSPF flooding like a news bulletin - you only rebroadcast news that's fresher than what you already know. Old news gets ignored; identical news gets acknowledged but not re-aired; only genuinely new news gets passed along.

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