How does DDNS work locally to find my NAS?

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R

redleader

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  • #1
    I setup a DDNS account on my Synology and got a certificate so that I could use HTTPS:

    1718384526959.png

    Surprisingly, this works locally to access my NAS from the LAN and with no port forwarding setup on my router:

    1718384337861.png

    How does that work? Pinging the DDNS address returns only my external (ISP assigned) IP address, so how does Chrome know that my Synology is at 192.168.1.200? My router isn't doing it:

    1718384421127.png

    Is the IPV6 address somehow responsible for figuring out where the NAS is on the local network?
     
    R

    redleader

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  • #3
    Paladin said:
    Does your router have a loopback feature enabled or NAT/DMZ hole and port forward or something?
    Click to expand...
    Its a really old linksys with few options. DMZ is disabled, and the Synology is pretty new, I don't think I've even changed a setting in it since I got the device, so no way I've put in the .200 address somewhere.

    Digging into it, I think it must be the IP6 address, since the DDNS is resolving to an IP6 address, and (iirc) those are universally addressable. If so, that would be pretty cool. Is there someway in Chrome to see if a name is resolved using IP4 or IP6?
     
    Paladin

    Paladin

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  • #4
    Ah oh yeah, if you have IPv6 working on your network, it is almost certainly that. IPv6 allows multiple addresses per interface and no NAT so if your ISP is giving you IPv6 then the IP from the ISP is right on the NAS as opposed to on the router WAN interface and then NAT for the IPv4 address on the NAS network interface.

    You can look at the console in Chrome (F12) and then look for the network tab to see what IP addresses and connections are going on in a page load. It will show a list of 'jobs' or requests and you click on one to see the details and you should be able to see the IP addresses involved in the column with the details (Headers or other columns).
     
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