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I am currently studying my home network router Sys Routing Table and attempting to resolve WHY my Public IP (assigned by my ISP), Gateway IP (WAN) and Destination Network (WAN) are all different.

I assume the Gateway IP would be identical to my Public IP as I believe the Destination Network IP is an internal network at my ISP.

For example, this is what I am seeing:

Destination Network (WAN): 205.211.222.192
Gateway IP (WAN): 205.211.222.254
Public IP: 205.211.222.208

It appears the ISP has a different Gateway IP assigned to my router as the Public IP is obviously not a match.

From what I can tell, the Destination Network is an internal network at the ISP.

The Gateway IP is a secondary IP, assigned to my router. Public IP is another IP, assigned to my router?

The latter two points is where I am confused.

I did some pretty intense research on this and getting mixed results and answers as to why this is happening.

I am not running any independent Firewalls or otherwise. Just a standard TP-Link Archer C9 with default settings.

This was another article I read on this exchange, but seemed to be a variant issue (different setup):

https://networkengineering.stackexchange.com/questions/20063/why-is-my-routers-wan-ip-different-from-public-ip

I did some further research and received some data about the fact that this could be related to a subnet requirement of the ISP, but it's still not clear.

  • The Public IP is the IP address assigned to your modem. The gateway IP is the next hop for that network - some other ISP device. I don’t know what the destination network IP is - likely something specific to how your ISP does things. – Appleoddity Jun 24 '18 at 16:04
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This looks completely normal to me.

205.211.222.192/26 (The 26 is derived form the fact that 192 is the lowest address in that subnet and 255 is the highest making for a 64 address subnet) is the subnet at your ISP into which your router connects its WAN port.
The default gateway on that subnet is 205.211.222.254, which your router is to use as its WAN gateway to reach the rest of the internet.
Your router gets 205.211.222.208 as its own WAN ip-address in that subnet and which is also its public IP.

205.211.222.192/26 is NOT an internal network. It is a public network which according to the WHOIS registration belongs to "Honduras Tegucigalpa Amnet Cable Tegucigalpa" which is an ISP in Honduras. (They can have rented out this range to another ISP though. This sometimes happens.)
It is quite possible other addresses in this subnet are allocated to other customers of your ISP. It is very unlikely you got that whole 64 address subnet to yourself.

  • Good catch. I didn’t notice that the “destination network” was just the network address. – Appleoddity Jun 24 '18 at 16:21
  • @Appleoddity I've seen a fair number of SOHO routers that list the netmask and/or the size (in bits) of the network in a separate field away from the actual network address. For not so technical users it may not be clear these belong together so they often don't mention them in questions like these. It can even be worse. A few years ago I encountered a router that (hardcoded) assumed the netmask was always a /24 (and that for WAN and LAN). It even ignored the netmask it got from the DHCP on the WAN. It logged the DHCP parameters in the logs, but didn't actually use them. – Tonny Jun 24 '18 at 18:06

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