Forum Discussion
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. I have included primary DC and DR virtual server/ip's in pool and fall back ip as Primary DC virtual server IP but when both virtual server are down then in nslookup it's showing both primary and DR VIP ip's instead of only primary DC IP in fall back IP.
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
Altostratus
Hello Suresh, Can you post a snapshot of your pool configuration .
- suresh09_292033
Nimbostratus
Hi Kolom, attached both pool and dns resolution snap.
- suresh09_292033
Nimbostratus
Dns resoltuon snap
- kolom_265617
Cirrostratus
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
Nimbostratus
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
Nimbostratus
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?
- kolom
Altostratus
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
Nimbostratus
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
Nimbostratus
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?
- Jason_Brown_314
Nimbostratus
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.
- suresh09_292033
Nimbostratus
Thanks Brown, your suggestion worked for me.
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