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[chenks]

ok here's a theoretical question.

say current ISP provides static IPv4 IP address (just the 1).
own a domain name via 123-reg where the A record points to said static IP from ISP (with website being hosted locally).
all works fine.

however, if one should change ISP that doesn't supply a static IP then the whole thing falls down.

so is there solution that would "get around" such a problem? ie some way for the A record to point to something that then knows what the current ISP assigned IP address is?

[jelv]

Yes - you'd need to use a dynamic DNS service which associates a name with your current IP address.

https://www.1and1.co.uk/digitalguide/server/tools/free-dynamic-dns-providers-an-overview/

[andyfitter]

Google DNS is pretty good. It lets you use dynamic DNS on hosts within your own domain, rather than being forced to use hosts within some subdomain chosen for you.

[chenks]

Yes - you'd need to use a dynamic DNS service which associates a name with your current IP address.

https://www.1and1.co.uk/digitalguide/server/tools/free-dynamic-dns-providers-an-overview/

How would the help though?
Is the suggestion that I'd point the A record to the dyndns name? Which in turn then points to the IP?

I thought you could only use IP addresses on A records

[chenks]

Google DNS is pretty good. It lets you use dynamic DNS on hosts within your own domain, rather than being forced to use hosts within some subdomain chosen for you.

How does that work?

[andyfitter]

you register your own domain or transfer it into google management, and then you run a local app somewhere on your lan - Router/Pi etc. When your external IP changes the dynamic DNS record gets updated by the App.

The hostname that gets updated has a very short (or possibly zero) TTL so it barely gets cached. If your internet goes down and comes up again with a new IP there's a tiny window for DNS to serve the old address. The dynamic dns gives me an A record but I have a bunch of CNAMEs that point back the dynamic A record

This probably explains it better

https://support.google.com/domains/answer/6147083?hl=en-GB

I'm on a dynamic IP from Sky and have been using it for a couple of years. It's never failed me for external access via my own personal domain/hostname - I run a bunch of services - VPN endpoint, HTTPS via NGINX, these are secured by letsencrypt. It all works just as if it were a static ip.

[chenks]

intresting, and tranferring the domain to google will still allow me to make changes to A records and add TXT/SPF records?

for example, on 123-reg i currently have an @ A record and then a few specific sub-domain A records, and 2 TXT/SPF records for SSL purposes.

[andyfitter]

I believe you have full control of all your records types but best check first. Since Ive been using it I’ve noticed no difference between when I had a static IP

Edit.... 13 different record types including SPF

[chenks]

OK well i got it working (my edgerouter has built-in support for updating via the dyndns protocol).
am i right in saying that i need to add dyndns entry for each of the sub-domains i have (as well as the root). i currently have it configured with just a test sub-domain to see if it worked.

at present i have the following A records

@
www
and 9 sub-domains

i then have a "test" sub-domain configured in the dyndns section - there is no A record for the "test" sub-domain.

so can i have 1 dyndns entry that simply covers all possibilities?

is also see an opton to enable DNSSEC. is this something i should turn on?

[andyfitter]

I have a single hostname ‘www.xxx.co.uk’ updated via the dynamic protocol, for my ”primary” hostname and a bunch of other cnames pointing back to that hostname. Seems to work ok for me.

Don’t really know much about DNSSEC. I know it’s there as there are underlying flaws in the DNS protocol, but I think your router possibly needs to support it too as I’m sure yours would.

[chenks]

i'm not using cnames though.
each of my sub-domains are seperate "sites" and don't interact with each other.

[chenks]

all sorted

[andyfitter]

Glad it worked out for you. RE CNAMES - it made the most sense to me to just have the single 'master' dynamic record (home.abcdef.co.uk). My CNAMEs are for all the other sub domains that need to ultimately point to the same dynamic ip address, so vpn.abcdef.co.uk, nas.abcdef.co.uk, etc all CNAME back to home.abcdef.co.uk. 

Not that it matters, but I then use port forwarding on my router to NGINX running on a Pi to redistribute incoming traffic based on all the different CNAMES defined above.

 

[chenks]

this means i now don't have to be restricted to ISPs that offer static IP addresses