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| Thread ID: 22169 | 2002-07-13 10:43:00 | How often and in what way are DNS servers updated? | mike773 (978) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 62229 | 2002-07-13 10:43:00 | Recently (3 days ago) we changed ISPs at work, and to my amazement I managed to reconfigure our mail server fairly easily. Because of this our IP address changed, and we went from a mail-bagging arrangement to actually having our server live on the net. (A bit scary really!!) Now...problem is some DNS servers around the place seem to still have the old info and hence are sending mail to the old ISP who is rejecting it. In fact my home ISP has the old info the primary DNS, and the new info in the secondary DNS. I assumed the change would take at least a day or so to be picked up by all the world's DNS servers (and longer for some in weird places maybe). But...3 days seems a bit long. And why would the primary and secondary DNS have different info? Don't they talk to each other? I assumed the new data would be sent out from the new ISP and picked up eventually by everyone. Is this not right? Or is it just my ISP? I've e-mailed my ISPs helpdesk to ask them what the update interval on their DNS is and why the 2 servers are different, but I don't have a reply yet. Any ideas much appreciated! :-) |
mike773 (978) | ||
| 62230 | 2002-07-13 11:03:00 | when this forum changed IP addresses it was in excess of 4 days from memory, came right in stages...much like you are finding. It will depend on the TTL (Time To Live) parameters on IP I assume??? |
godfather (25) | ||
| 62231 | 2002-07-13 12:33:00 | Each ISP will vary. Three days is standard, so a change request is usually implemented on a Friday. Internet DNS information is stored at the root servers. DNS resolvers are sited around the world. So once your SOA record is changed at your ISP, their DNS servers will advise nearby resolver servers. In this link at step 2, you can see that some ISPs may only update information from the root/resolver servers every 2-3 days www.valueweb.net Here is another link that explains DNS and why it takes so long to update the world www.internic.net Your new ISP primary DNS server will resolve DNS queries from other ISPs that have your new ISP as the SOA, so it doesn't really matter if the secondary one has not updated yet. |
Marty2001 (421) | ||
| 62232 | 2002-07-13 22:07:00 | Thanks Godfather and Marty. I knew someone would know! Looks like I'll have to wait a couple more days to be sure. Although the ISP I use at home (shall remain anonymous) still has the old info in the primary DNS and the new info in the secondary DNS. That seems weird since I thought the secondary DNS would be a mirror of the primary one. I can send mail to myself at work from hotmail, but not from my ISP account! :( |
mike773 (978) | ||
| 62233 | 2002-07-14 04:05:00 | You should tell your ISP about that. Their secondary should be updated by a zone transfer from the primary , never, ever, directly. That's why it is called a "secondary". If they are trying a primitive form of load sharing on their nameservers, it's about time they did it correctly. I suppose that neither will be an authoritative server -- they'll be caching local servers --- but both should have the same data. |
Graham L (2) | ||
| 62234 | 2002-07-14 06:41:00 | Hi Graham Yeah, that's what I thought. I have e-mailed the helpdesk, but since it is the weekend maybe their DNS guru is not there. Glad my thinking was right though. So glad there's so many knowledgeable people about! :-) |
mike773 (978) | ||
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