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suresh09_292033's avatar
suresh09_292033
Icon for Nimbostratus rankNimbostratus
Jan 23, 2018
Solved

Fall back IP

What i understanding regarding fall back IP is that if all virtual servers in pool associated with wide ip are down then DNS will resolve to fall back ip but in my scenario it's happening differently...
application delivery
BIG-IP DNS
devops
  • Jason_Brown_314's avatar
    Jason_Brown_314
    Jan 31, 2018

    You need to have the alternate set to fallback for this to use that IP entry.

     

    Also, just to expand - I have just experienced this too and I understand that there is a level of caching done within DNS express in order to try to expedite the reply, you are also using a LDNS (presuming 10.10.10.10 isn't the DNS listener) to resolve this host you could get old answers. I disabled DNS express in my profile and it worked as I expected it should.

     

    being new to the GTM I am also still learning, so this is based on my troubleshooting only.

     

kolom's avatar
kolom
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Jan 25, 2018

Hello suresh,

 

This behavior is caused by using "Return to DNS" as a fallback method.Return to DNS drops the resolution to BIND. When this mode is used, the typical response will be a list of all virtual servers associated with the Wide IP.

 

  • suresh09_292033's avatar
    suresh09_292033
    Icon for Nimbostratus rankNimbostratus
    Jan 25, 2018

    Thanks Kolom for quick reply, i will try by disabling return to dns option.

     

    Can you please help me to understand the below line from F5 site. "You can also use Return to DNS when you want to limit a pool in a single pool configuration to only one or two load balancing attempts"

     

  • suresh09_292033's avatar
    suresh09_292033
    Icon for Nimbostratus rankNimbostratus
    Jan 31, 2018

     

    I have disable return to dns from fallback method but still its resolving both virtual server ip's in dns. What could be the issue?