Discuss Nokia 4A0-100 Exam Topic 4 Question 124

Which of the following routing protocols cannot be used between routers R2 and R4?

AStatic Routing

BIS-IS

COSPF

DeBGP

Suggested Answer: D

In the diagram:

R2 and R4 are both within AS 65540, which indicates that they are in the same Autonomous System.

eBGP (External Border Gateway Protocol) is designed for routing between different ASes (inter-AS routing).

Since R2 and R4 are in the same AS, you would use:

OSPF or IS-IS (both interior gateway protocols -- IGPs)

Static routing is also valid between any two routers if manually configured

eBGP is invalid between routers in the same AS.

The correct protocol in that case would be iBGP (internal BGP) if BGP were to be used within the AS.

Therefore, the correct answer is: D. eBGP

Nokia IP Routing Fundamentals -- BGP vs IGP

Nokia SRA Guide -- AS Concepts and Protocol Suitability

RFC 4271 -- BGP Specification

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21 comments · newest first

Lajuana 1 month ago

So, eBGP is definitely the odd one out here!

Xenia 2 months ago

OSPF is also internal. Static routing works too.

Art 2 months ago

IS-IS is for internal routing, so it's fine.

Tamra 2 months ago

I feel unsure about IS-IS. Is it really not usable?

Deeann 2 months ago

Agreed! eBGP is for different AS.

Johnathon 2 months ago

I think it's D) eBGP. Can't use it between same AS.

Clorinda 2 months ago

I’m leaning towards eBGP too. It’s not suitable here.

Ula 3 months ago

IS-IS is also a good choice, but not for this case.

Glendora 3 months ago

Static Routing could work, but not eBGP.

Jeff 3 months ago

I feel confident about OSPF being valid.

Joseph 3 months ago

Agreed, eBGP won't work here.

Adolph 3 months ago

I think it's D) eBGP. It’s for different AS.

Jame 4 months ago

I didn't expect static routing to be an option!

Rory 4 months ago

Wait, can IS-IS even work in this scenario?

Christiane 4 months ago

eBGP is not applicable between those routers.

Rodolfo 5 months ago

I think OSPF is the right choice here.

Kenneth 6 months ago

Static Routing can definitely be used.

Adell 6 months ago

I’m pretty certain that IS-IS is more for interior routing, but I need to double-check that.

Erasmo 6 months ago

I feel like eBGP is used for inter-domain routing, so maybe it can't be used between R2 and R4?

Berry 6 months ago

I practiced a similar question where OSPF was the answer, but I can't recall if it applies here too.

Georgiana 7 months ago

I think I remember that static routing can definitely be used, but I'm not sure about IS-IS.

Nokia 4A0-100 Exam - Topic 4 Question 124 Discussion