H12-821_V1.0 · Question #748
In a broadcast or NBMA network, not all neighbors will establish adjacency relationships.
The correct answer is A. TRUE. On broadcast (e.g., Ethernet) and NBMA networks, OSPF elects a Designated Router (DR) and Backup Designated Router (BDR) to reduce the number of adjacencies formed. All routers form full adjacencies only with the DR and BDR - routers classified as DROther form only a 2-Way…
Question
Options
- ATRUE
- BFALSE
How the community answered
(49 responses)- A76% (37)
- B24% (12)
Explanation
On broadcast (e.g., Ethernet) and NBMA networks, OSPF elects a Designated Router (DR) and Backup Designated Router (BDR) to reduce the number of adjacencies formed. All routers form full adjacencies only with the DR and BDR - routers classified as DROther form only a 2-Way relationship with each other, never reaching the Full adjacency state. This makes option A correct: not every neighbor pair will establish a full adjacency. Option B is wrong because it assumes all neighbors fully adjoin, ignoring the DR/BDR election process that deliberately limits adjacency formation to reduce LSA flooding overhead.
Memory tip: Think of the DR as the "class president" - everyone fully connects to the president and VP (BDR), but the rest of the class (DROthers) just acknowledge each other with a wave (2-Way), not a full handshake.
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