800xA Preferred DNS and Alternate DNS
I have aestion about preferred DNS and Alternate DNS in 800xA system configuration
Suggested example from ABB is:
Enter Preferred DNS and Aleternate DNS as 172.16.4.1 and 172.16.4.2
What will happen if the entire primary network is down ?
Still other computers able to resolve the names; since the secondary network is operational?
Does RNRP will take care ?
Please refer to the attachment.
One of the purposes with RNRP is to make network redundancy transparent for applications.
If primary network is lost, RNRP will adjust the routing table in less than one second* (inject secondary as route for primary addresses).
*) The Max Lost Telegrams setting is just delaying the reporting in RNRP Monitor and System Alarm List.
Ergo: define primary addresses only and trust RNRP to ensure target is reachable even if primary network is down.
For DC nodes it may be an idea to supply other DC node as primary DNS server and self as secondary.