Distance Vector

Question 1

Distance Vector

Answer 1

Example: RIP v1 & v2
• EIGRP – advanced distance vector
• Periodic updates
• Exchange entire routing table with 
“directly connected routers”
• RIPv1 – sends updates via broadcast
• RIPv2 – sends updates via multicast
• Slow convergence – causes routing loops

Question 2

Link State

Answer 2

Example: OSPF & IS-IS
• Triggered updates – updates sent when 
there is a “change”
• Only the change is sent to every other 
router
• Multicast
• More robust
• No routing loops

Question 3

AD – administrative distance

Answer 3

AD – administrative distance (level of
trustworthiness of a route)
- Used when a router has two or more routing
sources configured (i.e. C, S, D, O, R)
- The router will use the source with the lowest
AD.

Question 4

Metric

Answer 4

Metric – what a dynamic routing protocol uses to
make “best path” decisions
- OSPF: cost (bandwidth)
- RIP: hop count

Question 5

Default ADs

Answer 5

Default ADs
0 – Directly connected (C)
1 – Static (S)
20 – EBGP
90 – Internal EIGRP (D)
110 – OSPF (O)
115 – IS-IS
120 – RIPv1 & v2 (R)
170 – External EIGRP
200 – IBGP

Question 6

3 Ways Routers Learn Routes to Destination Networks

Answer 6

3 Ways Routers Learn Routes to Destination Networks
1. Directly connected
2. Static – administrator configuresthe route
Rtr1(config)#ip route [destination network] [subnet mask] [next hop address OR exiting int]
S* - static default route – route used when destination route/network is missing
Rtr1(config)#ip route [0.0.0.0] [0.0.0.0] [next hop address or exiting interface]
How it looks in the routing table: S* 0.0.0.0/0
Host route
Rtr1(config)#ip route [dest. host] [subnet mask] [next hop address]
3. Dynamic routing protocols(RIP, EIGRP, OSPF)

Question 7

3 Ways Routers Learn Routes to Destination Networks

Answer 7

3 Ways Routers Learn Routes to Destination Networks
1. Directly connected
2. Static – administrator configures the route
Rtr1(config)#ip route [destination network] [subnet mask] [next hop address OR exiting int]
S* - static default route – route used when destination route/network is missing
Rtr1(config)#ip route [0.0.0.0] [0.0.0.0] [next hop address or exiting interface]
How it looks in the routing table: S* 0.0.0.0/0
Host route
Rtr1(config)#ip route [dest. host] [subnet mask] [next hop address]
3. Dynamic routing protocols(RIP, EIGRP, OSPF)