Is this on, or off-topic?
Let me start by clarifying one thing that directly impact my answer to this particular question. While the OP did mention "kernel IP table" this was a mistake on their part (or a translation issue). This is actually the routing table from the device. It has nothing to do with the Linux firewall "iptables".
As such, I personally feel it should probably have been left open. In essence it is asking "how do I understand this routing table" which is a perfectly valid question on this site.
This isn't a question about host configuration. It doesn't really matter if the device it was pulled from is an end device or a router/gateway/firewall. It is simply a matter of understanding the information presented in a routing table.
To me, that is pure networking and on topic to be answered here. Whether there are many similar answers on other sites of SE really doesn't matter at this point.
I believe this could go either way, but only for a very specific reason: What topics can I ask about here? specifically states the following as on-topic:
"servers operating as a router/switch/firewall"
While it is pretty clear from the question that this is some form of linux server it is NOT definitively clear whether this server is operating as a "router/switch/firewall" as it was not specified by the OP.
While it is tempting to assume that this is not the case, I believe that clarification should have been requested from the OP first before immediately closing the question. We simply didn't have enough information to confirm whether the question was off-topic or not. I don't believe SE should take the stance of a question being invalid unless proven otherwise. I see this more on SO with duplicate question flags than NE, but this has actually been the reason I have stopped myself from asking questions on SO and instead used other resources to get my questions answered- to avoid fighting moderators and spending more time proving my question is relevant than looking for an answer.
Moderators perform a very important role in keeping the questions, answers, and users relevant to the site and overall improving the value of the site to its users, but any negative actions can have a very strong effect on users and IMO should be used sparingly or when the situation is clear enough to dictate action. I don't disagree that this question is likely off-topic as this was likely just an endpoint server, but I think that decision was made without enough information, which can contribute to more confusion than clarification for users and can lead to a cold, unwelcoming feel to this site.