I've been dealing with a frustrating issue after moving our company website to a new host last week. I updated the A records and CNAME at our registrar to direct to the new server IP. Everything seems good on the outside—global propagation checkers show that DNS changes are complete and every location shows the new IP address. However, around 2% of our clients are experiencing a "Page not found" error when trying to access the site. I've suggested they clear their browser cache, but that didn't help. One client even ran an nslookup and is still seeing the old IP. I lowered the TTL to 300 seconds before making the switch, which I thought would prevent this issue, and the old host is completely shut down. Is it possible their local ISP DNS is holding onto cached records for this long? How can I resolve this now, and how can I avoid a similar situation in the future?
5 Answers
You might want to suggest clients clear their DNS cache. Running "ipconfig /flushdns" could help. Additionally, be aware that if users have any manually set host files, that might cause inconsistencies too. Could be that a previous setup caused some odd configurations that are still in play.
It sounds like you might be dealing with a local DNS cache issue or even a problematic host file. If some clients are still seeing the old IP, it could be that their DNS provider hasn't updated yet. To check this, have them run an nslookup and see which DNS server they're hitting. Sometimes, if the old DNS server is still active in some capacity, it might be responding with outdated records. Also, if clients are on a private network, they might have internal DNS settings affecting the results.
If almost all of your users are fine except a small percent, this seems like it’s more of a local problem for those clients. As for preventing these DNS zombie states in the future, always wait out the original TTL before decommissioning the old host. This precaution helps ensure everyone has the latest information.
One thing to consider is the TTL you had before lowering it. If it was set to something like a week, you may need to let that original TTL expire before clients start seeing the new records. Going forward, don't turn off the old host until you're confident the new setup is fully functional. It could save a lot of headaches. Plus, always verify which DNS servers are being used by your clients.
I recommend checking if there's any custom or local DNS configuration at the clients’ end. Sometimes, if a business has a local DNS server set up, it could override public DNS records. I had a situation before where an old DNS zone stayed active and caused similar issues. If possible, get them to use a public DNS service like Google’s (8.8.8.8) temporarily to see if that resolves the issue.
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