Failover for internet line through DNS
Posted on 2004-10-18
let me first explain what we are trying to do:
We have one apache server and two netgear routers. Each router has it's own static external IP adress. Each router uses a different internet line (aka ISP) so if one ISP goes down, the other one should still operate (of course this depends on which backbones the ISPs are actually using, but let's assume that one line can be up while the other one being down).
The server should be available under the DNS entry server.mycompany.com. It is typically reached through router 1 / internet line 1. But when line 1 goes down, server.mycompany.com should be reached via router 2 / internet line 2.
- router 1 is using a fast line and has IP address 18.104.22.168
- router 2 is using a slow (backup) line and has IP address 22.214.171.124
- DNS entry server.mycompany.com is pointing to 126.96.36.199
now, when the fast line is down, I want server.mycompany.com to be quickly updated to 188.8.131.52.
when talking to my ISP I was told that DNS updates from their side can take some time to propagate.
My questions are as follows
- how comes that services like dyndns.org see to propagate the updates within seconds ?
- can anybody think of another alternative to setup failover for internet lines ?
PS: just for the records - yes we have a backup server as cold stand-by :-)