Your node is 2540154 blocks behind (9.7 years) - even though it is not?

Question

I get this message that my node is 9.7 years behind even though it is at the current height.

Does this just mean that this IP is trying to send me wrong block height data?

LOG: IP.Address:18080[OUT] sync data returned a new top block candidate: 3098243 -> 5638397 [Your node is 2540154 blocks behind (9.7 years) behind] Synchronization started

Will the node know to check other nodes to see if this larger height number 5638397 is correct/incorrect or should I block that IP?

This happened couple days ago so I know the current height is not 3098243.

Edit: added a better title to this ask.

Answer 1

I had a similar issue in v0.18.3.2. It's my assumption this was some type of network attack, and downgraded back to v0.18.3.1. When v0.18.3.3 was released, I installed and after starting monerod I found these lines in my log:

I [XXX.XXX.XXX.XXX:18080 OUT] Sync data returned a new top block candidate: 3118923 -> 5033259 [Your node is 1914336 blocks (7.3 years) behind]
I SYNCHRONIZATION started
...
... (other nonsense here)
...
E Transaction not found in pool
I [YYY.YYY.YYY.YYY:18080 OUT] Sync data returned a new top block candidate: 3119199 -> 3119200 [Your node is 1 blocks (2.0 minutes) behind]
I SYNCHRONIZATION started

In other words, monerod is correctly identifying the top block and rejecting the bad block. This means there is nothing for you to do.

As a general rule of thumb, you manually blocking IPs causes more harm then good, so don't do it unless you are 100% certain you want to block that IP. Consider, for example, how many people have their monero node behind a VPN; blocking the VPN's ip won't stop the bad nodes, won't help you solve the problem, and will block you off from good nodes.