Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:00,000 --> 00:00:06,000 align:middle line:84% However, what happens when the subnet masks are different? 2 00:00:06,000 --> 00:00:08,000 align:middle line:84% Let’s expand on our previous example 3 00:00:08,000 --> 00:00:11,000 align:middle line:84% in this example, we have 4 routers 4 00:00:11,000 --> 00:00:18,000 align:middle line:84% router 4 is learning about network 10.1.1.0/27 5 00:00:18,000 --> 00:00:21,000 align:middle line:84% from router 1 via RIP version 2 6 00:00:21,000 --> 00:00:30,000 align:middle line:84% router 4 is learning about network 10.1.0.0/16 from router 2 via BGP 7 00:00:30,000 --> 00:00:39,000 align:middle line:84% and router 4 is learning about network 10.0.0.0/8 from router 3 via OSPF. 8 00:00:39,000 --> 00:00:43,000 align:middle line:84% Notice the administrative distances RIP is 120 9 00:00:43,000 --> 00:00:48,000 align:middle line:84% BGP is 200 in this example, OSPF is 110 10 00:00:48,000 --> 00:00:57,000 align:middle line:84% which way will router 4 send traffic if you ping 10.1.1.1 on router 4. 11 00:00:57,000 --> 00:01:01,000 align:middle line:84% Will it go to router 1? Because of the routes received via RIP 12 00:01:01,000 --> 00:01:04,000 align:middle line:84% or will it let go to router 2 or will it go to router 3? 13 00:01:04,000 --> 00:01:10,000 align:middle line:84% Notice OSPF has a lower administrative distance than RIP 14 00:01:10,000 --> 00:01:13,000 align:middle line:84% and RIP has a lower administrative distance than BGP. 15 00:01:13,000 --> 00:01:17,000 align:middle line:84% Which path is chosen by router 4? 16 00:01:17,000 --> 00:01:21,000 align:middle line:84% The important lesson here is that the length of the route 17 00:01:21,000 --> 00:01:25,000 align:middle line:84% takes precedence over administrative distance. 18 00:01:25,000 --> 00:01:28,000 align:middle line:84% In other words, administrative distance is only used 19 00:01:28,000 --> 00:01:32,000 align:middle line:84% if multiple routing protocols are trying to put 20 00:01:32,000 --> 00:01:35,000 align:middle line:84% the same route into the routing table. 21 00:01:35,000 --> 00:01:40,000 align:middle line:84% Router 4 is learning about network 10.1.1.0/27 22 00:01:40,000 --> 00:01:47,000 align:middle line:84% 10.1.0.0/16 and 10.0.0.0/8 23 00:01:47,000 --> 00:01:53,000 align:middle line:84% the router will see this as 3 separate and distinct routes. 24 00:01:53,000 --> 00:01:59,000 align:middle line:84% the 3 routes will be put into the routing table as they are seen as separate routes 25 00:01:59,000 --> 00:02:09,000 align:middle line:84% but out of the 3 of them, network 10.1.1.0/27 is chosen as it has the longest match. 26 00:02:09,000 --> 00:02:15,000 align:middle line:84% So, in other words, the ping from router 4 will go via router 1 27 00:02:15,000 --> 00:02:19,000 align:middle line:84% because it’s the best match or longest match in the routing table 28 00:02:19,000 --> 00:02:25,000 align:middle line:84% even though RIP has a high administrative distance than OSPF 29 00:02:25,000 --> 00:02:30,000 align:middle line:84% longest match routes take precedence over administrative distance. 3432