LInk Controller Mail domain delegation

Hi Techgeeeg,

 

the CNAME response comes from your authoritative nameserver. There we have the so called delegation, to get the Link Controller involved into the name resolution process.

 

So the CNAME is required to return a hostname in a subdomain, which is handled by the Link Controller.

 

Now your local resolver will send a new A-query which will be resolved by the Link Controller. The answer will contain an A-record (virtual IP address). (If you create a hostname-based WideIP, the Link Controller will automatically map the assigned virtual servers VIPs as a resource. The automatic mapping requires the virtual IP addresses to belong to the same address range as the self IPs on VLANs, associated with your internet links. Manual changes in the wideip.conf / bigip_gtm.conf and config reload may be required.)

 

That´s more or less like a zone file with multiple A-records for a single hostname in BIND. The difference is in the availablity checking done by the Link Controller. Typically it will return a single A-record only, depending on the selected load balancing algorithm and it´s availability.

 

The Link Controller will return CNAME records as fallback method only.

 

I´m wondering, if your question is related to the high availability of incoming mail?

 

Thanks and happy holiday,

 

Stephan

 

PS:

 

1) Due to the bank holiday my responses may be delayed.

 

2) Unfortunately I don´t have access to a Link Controller right now (I own just a LTM/GTM combo).