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ENCOR Exam - Question 211


How are the different versions of IGMP compatible?

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Correct Answer: C

IGMPv2 is compatible only with IGMPv1 because IGMP versions are designed to ensure backward compatibility with the previous versions. IGMPv2 can understand and process the messages from IGMPv1, but not the other way around. This compatibility allows networks that are incrementally upgraded to IGMPv2 to still interoperate with devices running IGMPv1, ensuring a smooth transition.

Discussion

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HeinThuOption: C
Dec 19, 2022

Compatible with other Versions of IGMP? IGMPv1 : No IGMPv2 : Yes, only with IGMP v1 IGMPv3 : Yes, with both IGMP v1 and v2

danman32
Jul 9, 2023

But if v3 is compatible with v2, wouldn't that make v2 also compatible with v3? If that's so then v2 is not ONLY compatible with v1.

ihateciscoreally
Aug 16, 2023

no man, another example is programming: C++ is compatible with C (C++ understands C syntax) C is not compatible with C++ (C doesnt understand C++ syntax).

ihateciscoreally
Aug 16, 2023

no man, another example is programming: C++ is compatible with C (C++ understands C syntax) C is not compatible with C++ (C doesnt understand C++ syntax).

diegodavid82
Feb 28, 2022

It's not exact but is the best answer because other options are false. IGMP V3 is compatible with V1 and V2 (and obvious V3), likewise, IGMP V2 is compatible with V1 (and obvious with V3). Finally, IGMP V1 is only compatible with V1.

Claudiu1
Nov 14, 2023

this question is downright idiotic

wr4net
May 15, 2023

if v3 is compatible with v2, then doesn't this imply that v2 is in some way able to work with v3, so it's too compatible with v3? seems like a stupid question. the only good answer is C though, so i agree with that.

danman32
Jul 9, 2023

I was thinking the same thing.

BeehurlsOption: B
Mar 11, 2024

I'm actually going to assume they are asking something different and say B... If C is correct then D is also correct because v3 is compatible with v2 and v1. When a router is configured with v3 it can process v1 and v2 requests, but a router configured for v1 or v2 cannot process a v3 request. Therefore, v3 is only compatible with v3. The question is definitely worded poorly and needs more context.

kthekillerc
Sep 2, 2021

Provided answer is correct

[Removed]Option: C
May 27, 2024

C is correct

elbruno
Jul 5, 2024

A and B are wrong because they compare similar versions. Leaving C and D.

Shri_Fcb10Option: C
Aug 23, 2024

C is right. v3 is only compatible with V2

c728f00Option: C
Apr 9, 2025

BACKWARD compatible