1
00:00:00,000 --> 00:00:04,000
However if we go back to the previous example

2
00:00:04,000 --> 00:00:10,000
note that in this case OSPF and RIP are advertising

3
00:00:10,000 --> 00:00:16,000
the same route network 10.0.0.0/8 is advertised

4
00:00:16,000 --> 00:00:22,000
by both New York and San Jose and thus administrative distance is chosen

5
00:00:22,000 --> 00:00:27,000
because the same route can’t be put twice into the routing table.

6
00:00:27,000 --> 00:00:30,000
The router has to choose the best route

7
00:00:30,000 --> 00:00:33,000
and in this case, administrative distance is used

8
00:00:33,000 --> 00:00:36,000
as the tie breaker between OSPF and RIP.

9
00:00:36,000 --> 00:00:40,000
So in summary administrative distance is only used

10
00:00:40,000 --> 00:00:44,000
if multiple routing protocols are trying to put the same route

11
00:00:44,000 --> 00:00:50,000
into the Routing Information Base or RIP also called the routing table

12
00:00:50,000 --> 00:00:53,000
In this example once again the 3 routes

13
00:00:53,000 --> 00:00:56,000
are seen as 3 separate and distinct routes.

14
00:00:56,000 --> 00:00:59,000
All 3 routes are put into the routing table

15
00:00:59,000 --> 00:01:03,000
and the routing decision is based on longest match or best match.

16
00:01:03,000 --> 00:01:09,000
So network 10.1.1.0/27 has the longest match

17
00:01:09,000 --> 00:01:12,000
so it’s deemed to be the best route.

18
00:01:12,000 --> 00:01:14,000
Traffic is forwarded to router 1

19
00:01:14,000 --> 00:01:19,000
even though RIP has a higher administrative distance when compared to OSPF.