Drag the features on the left to their corresponding routing protocols on the right.
OSPF elects both a Designated Router (DR) and a Backup Designated Router (BDR) on multi-access segments, while IS-IS elects only a Designated Intermediate System (DIS) with no backup equivalent, since re-election on failure is fast enough that a backup is not needed. OSPF has native network types (broadcast, NBMA, point-to-point, point-to-multipoint) giving it full support for NBMA and point-to-multipoint circuits, whereas IS-IS lacks a native NBMA mode and provides only limited support, typically requiring point-to-point sub-interfaces over NBMA clouds. OSPF also refreshes each LSA in its database on a 30-minute interval (LSRefreshTime), meaning the entire link-state database is periodically re-advertised every 30 minutes.
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