3.3 Describe how a routing table is populated by different routing information sources

From 3.2 blog post:

3.2.e Administrative distance

Administrative distance is the way Cisco routers chose between routes with the same prefix. Cisco favours some types of routes and routing protocols over others.
Refer to line 3 of the routing table above:

O 10.234.132.0/24 [110/2] via 10.200.20.46, 00:34:57, GigabitEthernet5/0

The square brackets hold the Administrative Distance and Metric (110 and 2 respectively). The O at the beginning at the line corresponds to OSPF, if you look below you will see OSPF has an Administrative Distance of 110.
Here is list of Administrative Distances:

0 => Connected
1 => Static
20 => BGP (external routes)
90 => EIGRP (internal routes)
100 => IGRP
110 => OSPF
115 => IS-IS
120 => RIP
170 => EIGRP (external routes)
200 => BGP (internal routes)
254 => DHCP default route
255 => Unusable

 

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