Website - DNS failover options

Forums › IT Pro and developers › Website - DNS failover options

wazzab

84 posts

Master Geek

#91141 7-Oct-2011 10:16

Hi all,

We host our websites and mail server locally, and have fibre (/28) into our building. We have just put in a redundant wireless internet (/29) link. Our Webserver and Mailserver (via NAT on the firewall) now have an 2 IP external address's each - one via the fibre and one via wireless. When primary fibre goes down I need to ensure Mail and Web traffic inbound to our organisation continues (outbound traffic auto swtiching between fibre and wireless is already working nicely). With, Mail I seem to be able to achive via a second/backup MX record.

What options do I have for IP or DNS redirection? Basically mydomain.co.nz DNS records point it to IP down the Fibre, and if Fibre goes down, I want traffic to go down Wireless? I can obviously log into my DNS portal for the website and change it and let the changes propagate, but this would use up some time?

Thanks

magu

Professional yak shaver
1599 posts

Uber Geek

Trusted

BitSignal

Lifetime subscriber

#530496 7-Oct-2011 10:26

If you can put a machine somewhere on the web to act as a failover/load-balancer, it could do the hard work for you. But that still leaves one SPOF.

The other option is to have incredibly shot TTL on the DNS records, so that propagating them when something changes doesn't take long. However, this is not guaranteed, as some ISPs ignore the TTL and cache records for longer.

I'd go with the load-balancer approach.

"Roads? Where we're going, we don't need roads." - Doc Emmet Brown

Zeon

3916 posts

Uber Geek

Trusted

#530499 7-Oct-2011 10:31

Insane mentioned Maxnet's hosted load balancing service which might work well for you, I would talk to them. But yea that's one big weakness with normal A or CNAME records in DNS, very difficult for failover.

Speedtest 2019-10-14

Ragnor

8222 posts

Uber Geek

Trusted

#531062 9-Oct-2011 00:04

Sounds like multi homing is needed for your site.

I think normally you choose one ip range as the primary (or get your own from APNIC), you use that address range for your A records.

This range is advertised via BGP over both your wireless and fibre connection in your routers with some setup for BGP failover.

If your fibre goes down both ends notice ie: your router and your fibre providers router, but there is still a route to the ip addresses you are using via the wireless provider.

http://en.wikipedia.org/wiki/Multihoming
http://en.wikipedia.org/wiki/Border_Gateway_Protocol

You probably want a network specalist to give you some advice on this and help set it up.

At work we had this setup before I started by http://ifm.net.nz/ - they seem to be highly regarded.

wazzab

84 posts

Master Geek

#531368 10-Oct-2011 08:57

Thanks all - not as easy as I would of expected. I found this out on there as well : http://www.dnsmadeeasy.com/enterprise-dns/dns-failover/

While we are not absolutely 100% uptime required, it would have been nice to have an easy solution for diversion. I will investigate your suggestions anyway. Thanks.

insane

3240 posts

Uber Geek

ID Verified

Trusted

#535004 18-Oct-2011 23:59

wazzab: Hi all,

What options do I have for IP or DNS redirection?

Zeon: Insane mentioned Maxnet's hosted load balancing service which might work well for you, I would talk to them. But yea that's one big weakness with normal A or CNAME records in DNS, very difficult for failover.

Sorry have been away on Holiday. Indeed we do provide a service which can do exactly what you need and does not have any single points of failure.

Fire me a PM if you need more info :)

Cheers,