Date: Tue, 23 May 2000 01:06:22 -0600 (MDT) From: "Forrest W. Christian" <forrestc@iMach.com> To: Craig Beasland <craig@hotmix.com.au> Cc: "'freebsd-isp@freebsd.org'" <freebsd-isp@FreeBSD.ORG> Subject: Re: Changing C Classes Message-ID: <Pine.BSF.4.21.0005230040090.19881-100000@workhorse.iMach.com> In-Reply-To: <A1FB33621BC3D311872D004005F62F6C5920@MANDELA>
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On Tue, 23 May 2000, Craig Beasland wrote: > We are about to move from one c class to another. Everything will need to > be moved from DNS to web to dialup servers. Does anyone have any advice on > the best way to do this with the minimum of downtime? The real issue here is moving the DNS - all of the others are relatively simple. Before I go into that - I'd recommend turning down your TTL timers in DNS to next to nothing at this point - that way, when you are ready to switch, the changes will take effect almost immediately - with a caveat. Look at the numbers in the SOA and if you can't figure out which ones to turn down, ask further. That said, the real problem is getting the DNS changed with your Registrar (usually Network Solutions). Hopefully, you aren't running both primary and secondary dns on the same network. (Obligatory plug: If you are look at http://www.backupdns.com). Or better put, if your secondary DNS Server isn't changing addresses, then this gets less tramatic. Your goal is to make sure that your DNS as visible to the internet is always available during the transition (MOST IMPORTANT) and that the A records in the DNS match whatever IP addresses you have assigned at that point (not quite as critical). We'll take these both separately: 1) Making sure your DNS is visible. As I said before, if your secondary (or primary) DNS server isn't changing IP addresses, you're home free. Basically, as long as one of the DNS servers work, things will get to you - although slightly slower at times (50% of the requests will have to give up after trying the "missing" server and then try the working one). If both of your DNS Servers are on the same network you should consider moving one off site (see plug above). If this isn't feasable, then I'd probably recommend submitting a address change request to the internic for one of them, then a couple of days after it takes effect, switch your IP's. In this way, one of the two is always available to the internet. After the change, then submit the change for the second one. Another option would be to run the old and new IP addresses in parallel (which I will ALWAYS do if possible) for some period. This requires creative routing at times. However, this has the benefit of giving you some time for everything to stabilize before dropping the old addresses. If this is remotely possible, please email me with specifics and we can talk about it.... The key here is that you MUST have at least one DNS server visible to the internet at any given time. 2) Keeping consistent data in the DNS. When you change the IP addresses, you should almost immediately change the DNS to reflect this. Remember, though, that these changes MUST take effect in whichever DNS Server is internet visible. If you have off-site secondary DNS you should coordinate the change of your primary's address in the secondary's configuration so that it occurs at the same time as the IP Address changes. This way, the secondary can get the changes from the primary which you can change. I'll re-mention the timers - by turning them down you can decrease the amount of time between when the secondary checks for updates. However, be careful not to turn down (I think) expires, because that is the amount of time before the secondary figures that the zone is stale and quits serving it - if anything this should be INCREASED. I realize this isn't too coherent - I need some sleep. Please ask questions to clarify if needed. Thanks. - Forrest W. Christian (forrestc@imach.com) KD7EHZ ---------------------------------------------------------------------- iMach, Ltd., P.O. Box 5749, Helena, MT 59604 http://www.imach.com Solutions for your high-tech problems. (406)-442-6648 ---------------------------------------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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