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DNS Flag Day

Kind of a big deal

DNS Flag Day

I hope everyone is getting ready for DNS Flag day on the start of February.  In short, major companies will refuse DNS queries from older non-compliant DNS servers.


At a minimum, I would use the test tool to make sure queries to your own domains will continue to work.

Head in the Cloud

Re: DNS Flag Day

Interesting.  I had no idea.  I decided to test a dynamic Meraki hostname and it seems there are some issues with


Screen Shot 2019-01-21 at 1.08.22 PM.png

Kind of a big deal

Re: DNS Flag Day

I tested and all was fine. It may be that because all servers and storage are in the Cloud, that everything got tidied up when that was implemented. About the same time, I also did a lot of tuning to minimise delays from mismatched packet sizes and recall some changes were DNS related.

I am overdue revisiting the packet size mismatch issue, as some network devices can now handle packets up to 9K in size, and the last time I addressed this issue, activities such as using the browser had become much more snappy. For anybody else considering diving into the murky waters of MTU and MSS, I would advise them that manufacturers define frame sizes differently  (Cisco uses different standards for different OS), so take nothing for granted.

Robin St.Clair | Principal, Caithness Analytics | @uberseehandel
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