I’m on at least 2 blocklists at this point for the crime of not having reverse DNS set up. I don’t know how rDNS works. No amount of reading Wikipedia is helping me understand what I have to do....
It’s not a DNS issue, as the afflicted users can get the correct IPs from nslookup.
You are correct; looking at the resolutions via Google’s toolbox, it seems to be resolving fine.
Traceroutes time out at consistent hops but it’s different per afflicted network. The only recurring name has been costumer.tdc.net
I did a couple of traceroute tests from a couple locations (two data centres, my local WiFi, and via cellular data), and they all seem to end at cpe.ae20-0.khk7nqp8.dk.customer.tdc.net. In teleco terms, cpe usually means “Client/Customer Premise Equipment”, so it wouldn’t surprise me if that is the address assigned to the network equipment closest to your server’s local network (think neighborhood hub, or PON on premise, something super close to the demarcation point). If everyone else is able to get that far, then I’m more inclined to think the drop is happening on your equipment, not your ISP’s equipment; but having said that, if this is a residential network (regardless if ISP is provisioning you gigabit connectivity via fibre or whatever), there will always be a likelihood for ISP to be doing more filtering.
If you don’t mind, what is the gateway you’re using? Is there an ISP gateway and then your own, or straight from ISP equipment into your network? Are there any (single/double) NAT going on? Are there’s any security/filtering options on (either) equipment(s)?
rDNS, how?
I’m on at least 2 blocklists at this point for the crime of not having reverse DNS set up. I don’t know how rDNS works. No amount of reading Wikipedia is helping me understand what I have to do....
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