From:  Klaus Mueller <>
Date:  04 Nov 2018 00:54:28 Hong Kong Time

DNS round robin: server advertise load


Thank you for [mentioning] Happy Eyeballs, but as I read in the current 
RFC , it will select the best entry 
until you get a connection, not if the server responds slowly after a an 
established connection. So I assume Happy Eyeballs is not real 

Could the browser do a switchover for DNS Loadbalancing, if he knew 
about the load or number of connections?

My best guess would be:
If the webserver provided a value of load (response HTTP-Header) to the 
client, the client could use another DNS entry, depending on a global 
threshold value.
The easiest way would be to send the systemload to the browser, when 
this value is over 1, the browser should try another entry from DNS for 
the next request.


PS: Of course webservers could implement fancy algorithms to manage 
their clusters (evacuation etc.). And a stressed webserver could 
recommend a specific entry, which the browser should consider (verifying 
against DNS entry).


Klaus Mueller