amazon web services - load balancer act weird -
i have created 2 instances website , connected them amazon load balancer. have placed dns name
of load balancer cname
people can view website domain:
*.domain.com
and
www.domain.com
now people can visit website , works. problem if people go domain.com
load balancer shows first instance, if people go www.domain.com
load balancer switches between instances perfect.
why happen , how fix it?
using cname record in zone apex not supported under dns standard , can cause no end of issues downstream caching dns servers doing unexpected things result. can't confirm 100% certainty causing issue reasonably sure , if isn't practice bring dns configuration standard.
in route 53 configuration zone apex record leave record set name blank, set type "a", , select alias radio box "yes", click on alias target , populate list of supported endpoints under account, choose load balancer shown under "elb load balancers".
aws doesn't best job explaining while correct in using cname record target elb www.domain.com zone apex record needs done alias route 53 turn standard "a" record return dns queries return ip of elb instance @ point in time low time live ensure when ip changes cached records don't cause issue.
i suspect may solve problem here, upstream dns provider may having issues zone apex cname , taking ip of destination server , caching instead. after complete changes route 53 configuration wait 6-24 hours take account how long upstream dns provider caching record or manually set dns server alternate dns server have not used before such google's public dns servers located @ 8.8.8.8 , 8.8.4.4.
hope helps.
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