Welcome back - new ISP connected
Posted by Magnus on 23 April 2002, 10:37 GMT
If you're reading this, your DNS has updated, and you are now looking at ticalc.org through our new ISP. SolNet is in the process of switching to KPNQwest as ISP, and ticalc.org has been moved to the new networks. This move have caused a short downtime due to DNS expiry for some users - but if you're reading this, your DNS has now updated. We hope this will give you even better uptime and better performance. Let us know at webmaster@ticalc.org if you have any problems due to the new connection.
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The comments below are written by ticalc.org visitors. Their views are not necessarily those of ticalc.org, and ticalc.org takes no responsibility for their content.
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Re: Welcome back - new ISP connected
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Tijl Coosemans
(Web Page)
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Even better uptime? That's going to be difficult to achieve I guess. Last time I remember the site was down was quite a while ago.
Anyway, what kind of connection do you have now, still the same 4MBit/s?
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23 April 2002, 11:06 GMT
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Re: Welcome back - new ISP connected
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Rob van Wijk
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So that is what happened. I was already wondering if your servers went down for the first time in... well, a pretty long time.
Does this change anything for the users, except for "better uptime" (you're already very close to 100% :)) and "better performance" (never had any trouble with that either)?
BTW. Did you know that the KPN in KPNQwest is a Dutch company?
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23 April 2002, 11:12 GMT
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Re: Welcome back - new ISP connected
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graphics_man_73-92+
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What is all the junk you're talking about? Its too confusing and what's the big deal about a new ISP
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23 April 2002, 11:13 GMT
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Re: Re: Welcome back - new ISP connected
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David Phillips
(Web Page)
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The university that ticalc.org gets it's internet access from is switching uplinks (ISP's). That isn't a big deal to the normal reader, but can be important to the site, and is interesting for those who care about what goes on with the site.
When you change uplink providers, you usually have to get new IP blocks (although they can be portable -- see www.arin.net). The Domain Name System (DNS) is what allows you to convert a hostname, such as www.ticalc.org, into an IP address. In this case, www.ticalc.org (a CNAME) actually points to ticalc.ticalc.org (an A), which points 62.65.69.3.
DNS servers cache DNS entries for a certain amount of time, which is determined by the minimum TTL (time to live) entry of the SOA (start of authority) record. So if your DNS server is caching the old IP address, and the webserver changes IP's, then you would not be able to access the website. The solution to the problem is to set very low TTL values before the IP address switch. For example, if you normally have TTL values of one day, then it could take up to a day before people can resolve the new IP address. So at least a day before hand, you would set the TTL to a low value, such as five seconds. This would ensure that after a day, any (correct) DNS servers that cached the hostname would expire it, and get the new record with the low TTL. The new record would not be cached for very long, due to the low TTL. Therefore, when the IP address is switched and the DNS record updated, everyone should see the new website immediately. The TTL for the record can then be set to a more normal value.
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23 April 2002, 15:58 GMT
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Re: Re: Re: Re: Welcome back - new ISP connected
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David Phillips
(Web Page)
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Umm, haha, wrong. DNS is not peer to peer at all. DNS is a hierarchy. There are thirteen root servers (a.root-servers.net through m.root-servers.net), from which all queries start. For example, to look up www.ticalc.org, the DNS resolver (often called server) first asks one of the root servers who is responsible for the .org domain. Then the server responsible for .org gets asked who is responsible for ticalc.org. Then the server resposible for ticalc.org gets asked about www.ticalc.org.
For a more detailed, technical explanation, take a look at the first part of the FAQ for the djbdns package. djbdns is a complete package that provides a DNS cache (dnscache), authoritative DNS server (tinydns), DNS lookup tools, a DNS resolver library, and much more. If you wanted to setup a DNS server or DNS cache, this is what you'd use (because BIND sucks). The weird characters at the front of IP addresses in the FAQ are there because that's the format that the tinydns-data (generates the cdb database for tinydns) data file uses.
http://cr.yp.to/ djbdns/faq/orientation.html (remove the space)
Isn't DNS fun?
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23 April 2002, 22:51 GMT
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