Redundant ISPs, how to configure?
Ok, we have a T1 and an ISDN.
We are running our own DNS servers and hosting mail and web. However, recently our T1 ISP had some problems and we were down for two days.
How can I plan for this and make an easy transition to the ISDN line and get back up and running ?
The problem I see is the IP addresses are different for the two different lines. So even if I re-configure the Firewall to use the new IP addresses, how do I re-populate the DNS quickly so we are not down for 24hrs or more.
Since we are using our own name servers and I can go to my domain registration and changes the name servers any time. How long do these changes take. I am not talking domain changes just Name server changes.
I was thinking if I have a name server up on the ISDN line all the time I could just go to my domain registar and change the name server and then any request made from the internet would be re-routed to the correct IP address.
Am I going about this the right way ? Any help would be appreciated.
Thanks
mairving posted this at 15:10 — 2nd May 2001.
They have: 2,256 posts
Joined: Feb 2001
First you don't want to have the DNS populate quickly. You want to have two separate name servers running. That way if one is down, you can switch to the other one. If you look at some of the larger ISP's, you will notice that some of them have 4. Most all have at least two running all the time.
Network Solutions processes all of their changes at 5am and at 5pm EST. If you get your request in early enough they might do it that day. I have never found them to move quite that fast. Generally you send them the form to make the change, they send it back and says that it has errors on it. Then they sit on it until you email them which they ignore. I guess you can tell I am not one of their biggest fans.
Hope this helps.
Mark Irving
I have a mind like a steel trap; it is rusty and illegal in 47 states
Christian_SEO posted this at 22:27 — 4th May 2001.
They have: 470 posts
Joined: Mar 2001
Here's my idea:
Set your domain up for primary and secondary name servers.
Have 2 DNS servers at your location; on on the T1(primary), one on the ISDN(secondary).
Use a firewall with 3 nics connected to each DNS server and the third to your LAN.
The firewall (Linux - modest box) uses NAT to translate to your LAN PCs.
Your PCs have 2 entries for the "gateway" in their config.
You now have 2 ways in and 2 ways out.
This is a simple plan and you should consult a "real" network engineer about the details. Feedback anyone? I only spent 10 minutes putting this idea together, but I think it's pretty sound.
T1----DNS1->|Fire|
ISDN--DNS2->|Wall|---> Lan, mail, etc.
Good Luck!
Christian
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