CCNA Quiz: Administrative Distance. Which route is selected and why? EIGRP, OSPF or RIP? CCNA | CCNP

Do you really understand Administrative Distance? Are you sure you know which route will be selected? Well, see if you an answer this quiz question! This is a practical demonstration using GNS3.

Cisco routers use Administrative to select the best path. But, it depends!

Administrative distance (AD) or route preference is a number of arbitrary unit assigned to dynamic routes, static routes and directly-connected routes. The value is used by vendor-specific routers to rank routes from most preferred (low administrative distance value) to least preferred (high administrative distance value). When multiple paths to the same destination are available in its routing table, the router uses the route with the lowest administrative distance. Router vendors typically design their routers to assign a default administrative distance to each kind of route that is used, however, this value can usually be adjusted manually by a network administrator.

#CCNA #AdminDistance #Routing

[cuios]

thank you David for investing your time and producing high quality and very informative videos

[amochswohntet]

great lesson.
I would have guessed that the reason for router 4 being the chosen route is that it is the most specific route, and that is true, but an important caveat to that is the fact that the routes are made though different lans.

[pretender]

I really like how David explain well every topic he takes specially this one, I've been looking for explanation on how this really work. Glad I saw this 👏👏

[khalidwains]

Very nice explained. I consider my networking journey without you impossible. Your teaching style is awesome. Keep posting new things. Thanks sir!

[ahmedabdulla]

Sir this is so clear explanation for a twisted idea, thanks.

[dhilipkumar]

Thank you so much David 👍 Your quiz questions are awesome!!

[kalyanparasuram]

It's a eye opener video in terms of AD values.

[davidleitman]

Thank you for clarifying this point for us David

[BertieBrink]

Great quality video sound and information thanks David! Enjoy the trip

[edyalcantarajr]

Great explanation, you definitely made things clear for me.

[alenbilic]

great work david. would be good to see more ccnp related vids

[Mehdikun]

Brilliant explanation .. thank you david.

[saibot]

Very interesting topic. I need to do more research on the longest match I honestly had not even thought of that

[ifybruno]

I love this video David.. Thanks sooo much for this...

[hulkmarvel]

Thanks man was very useful I didn't knew this longest march rule...

[Itsmemayann_]

Hi it may be a dumb question, I understand the 3 routes listed are different, but why did it choose the RIP route in the original topology? was it because of the subnet? and chose the longest prefix? ??

[stackios]

Thank you David for this Quiz is very useful..

[sibakerokulafu]

hi sir david great tutorial for route selection . im just curious how you summarized the ospf from /32 to /24.. did you use summary address for ospf on the ABR which is R3?

[joeqfl]

I hope this helps someone....


Routing Table Order of Operations

1. Prefix Length - The longest matching or more specific route is preferred first, regardless of the dynamic routing protocols administrative distance.

2. Administrative Distance - If there are multiple routes to a destination with the same prefix length. The route with the lowest dynamic routing protocol administrative distance is preferred.

3. Metric - If there are multiple routes learned by the same dynamic routing protocol with the same prefix length. The route with the lowest metric is preferred.

3a. If two or more routes have equal metric values, then load balancing across routes may occur.

Summary:
1. Prefix Length
2. Administrative Distance
3. Metric
3a. Load Balancing

[ghibli]

more specific route overwrite less specific route
if there is route tiebetween routing protocols wins low administrative distance value