300-510 · Question #283
What are two major differences between OSPF and IS-IS routing protocols? (Choose two.)
The correct answer is A. OSPF uses IP protocol 89 foe encapsulation and IS-IS uses an IEEE 802 3 standard-based C. The OSPF DR role can be pre-empted only when the active DR goes down, but the IS-IS DR role. OSPF packets are carried as IP protocol 89, whereas IS-IS runs directly over the data-link layer using CLNS encapsulation rather than IP. In OSPF the DR is only replaced if it goes down (new routers, even with higher priority, cannot preempt it), while IS-IS will elect a new…
Question
What are two major differences between OSPF and IS-IS routing protocols? (Choose two.)
Options
- AOSPF uses IP protocol 89 foe encapsulation and IS-IS uses an IEEE 802 3 standard-based
- BThe OSPF default administrative distance is 115 and the default administrative distance for IS-IS
- CThe OSPF DR role can be pre-empted only when the active DR goes down, but the IS-IS DR role
- DOSPF partially refreshes the LSA database every 30 minutes, and IS-IS refreshes the complete
- EAn OSPF-enabled router is part of only one area but an IS-IS-enabled router is part of multiple
How the community answered
(24 responses)- A92% (22)
- B4% (1)
- D4% (1)
Explanation
OSPF packets are carried as IP protocol 89, whereas IS-IS runs directly over the data-link layer using CLNS encapsulation rather than IP. In OSPF the DR is only replaced if it goes down (new routers, even with higher priority, cannot preempt it), while IS-IS will elect a new DIS immediately if a higher-priority router joins the LAN.
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