CCNA 200-301 v1.1 quick lookup

Protocol defaults and timers

Default timers and behaviors worth memorizing, with the platform and protocol qualifications that apply.

From Rapid PVST+ — the same block lives in that article

Defaults are per standard and Cisco implementation; verify platform docs for exact values.
Parameter	Classic STP (802.1D)	Rapid PVST+ (802.1w)
Hello interval	2 s	2 s
Max age	20 s	3 missed hellos (~6 s) triggers reconvergence
Learning states	Listening 15 s + Learning 15 s	Discarding → learning → forwarding, often sub-second with edge ports
Convergence	~30–50 s	Sub-second on point-to-point links via proposal/agreement
Port cost (default)	Bandwidth-derived (e.g., 1G = 4)	Same cost model

Defaults are per standard and Cisco implementation; verify platform docs for exact values.

From OSPF network types and DR election — the same block lives in that article

Hello/dead must match between neighbors; mismatched timers alone prevent adjacency.

From CDP and LLDP — the same block lives in that article

Values are platform defaults — verify against your device documentation.

From First-hop redundancy protocols — the same block lives in that article

With HSRP preemption off, a recovered higher-priority router does NOT take back the active role (VRRP would preempt).
Parameter	Default
Hello timer	3 s
Hold timer	10 s
Priority	100 (higher wins)
Preemption	Disabled by default
Virtual MAC (HSRPv1)	0000.0c07.acXX — v2 uses 0000.0c9f.fXXX; the MAC alone does not identify the physical active router

With HSRP preemption off, a recovered higher-priority router does NOT take back the active role (VRRP would preempt).