dynamic routing
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CCNA Dynamic Routing Protocols — Flashcards
Static vs Dynamic Routing
1. What is static routing? – Manually configured routes using ip route
2. What is dynamic routing? – Routers automatically discover and adapt to paths using protocols
3. Which is more scalable? – Dynamic routing
4. Which adapts automatically to network changes? – Dynamic routing
5. Which is simpler for small networks? – Static routing
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Network vs Host Routes
1. What is a network route? – Route to an entire subnet (mask < /32)
2. Example of a network route? – 192.168.4.0/24
3. What is a host route? – Route to a single IP (/32 mask)
4. Example of a host route? – 10.0.12.1/32
5. How to configure a static host route? – ip route <host> 255.255.255.255 <next-hop>
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Dynamic Routing Operation
1. What is an adjacency? – Neighbor relationship between routers to exchange routes
2. What do routers advertise? – Their connected networks and learned routes
3. What happens if a link fails? – Routers remove invalid routes and switch to backups
4. What mechanism prevents dead‑end traffic in dynamic routing? – Automatic adaptation
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Categories of Dynamic Routing Protocols
1. What are Interior Gateway Protocols (IGPs)? – Share routes within one AS
2. Examples of IGPs? – RIP, EIGRP, OSPF, IS‑IS
3. What are Exterior Gateway Protocols (EGPs)? – Share routes between ASs
4. Example of EGP? – BGP
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Algorithm Types
1. What are distance vector protocols? – Share routing tables with neighbors (“routing by rumor”)
2. Examples of distance vector protocols? – RIP, EIGRP
3. What are link state protocols? – Build full network topology maps using LSAs
4. Examples of link state protocols? – OSPF, IS‑IS
5. What are path vector protocols? – Share AS path info for inter‑AS routing
6. Example of path vector protocol? – BGP
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Metrics
1. What is a metric? – Value used to determine best path within a protocol
2. Which protocol uses hop count? – RIP
3. Which protocol uses cost based on bandwidth? – OSPF
4. Which protocol uses bandwidth + delay? – EIGRP
5. Which protocol uses AS path? – BGP
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Equal Cost MultiPath (ECMP)
1. What is ECMP? – Load balancing across multiple equal‑cost routes
2. When does ECMP occur? – Same destination, same prefix length, same metric
3. How does traffic flow in ECMP? – Distributed across equal‑cost paths
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Administrative Distance (AD)
1. What is Administrative Distance? – Cisco value ranking route trustworthiness
2. Which AD is most preferred? – Lowest value
3. AD for connected routes? – 0
4. AD for static routes? – 1
5. AD for EIGRP summary routes? – 5
6. AD for external BGP? – 20
7. AD for internal EIGRP? – 90
8. AD for OSPF? – 110
9. AD for RIP? – 120
10. AD for external EIGRP? – 170
11. AD for internal BGP? – 200
12. AD for unknown routes? – 255 (unreachable)
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