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SMilanic's avatar
SMilanic
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May 13, 2022

GTM/DNS as a smart DNS server ("without" LTM)

Hi, I am trying to figure out a way to use F5 BIG-IP GTM/DNS as a smart DNS server only. The idea is shown in the figure below. There a two data centers with GTMs, LTMs and servers as shown a...
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Nikoolayy1's avatar
Nikoolayy1
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F5 GTM(DNS) can work directly with 3-rth party servers without LTM and you may use health monitors like SNMP or ICMP or HTTP/HTTPS for the monitoring:

 

https://techdocs.f5.com/kb/en-us/products/big-ip-dns/manuals/product/bigip-dns-implementations-12-1-0/21.html

 

Better to also configure a prober pool to select which BIG-IP devices (LTM or DNS/GTM) will send the probes to the generic hosts as otherwise the F5 devices will use and automatic algoritam to delegate the monitoring to one of them that will inform the other F5 devices if the servers are up:

 

https://support.f5.com/csp/article/K08433560

 

https://support.f5.com/csp/article/K10385

 

 

You can use DNS irules to make more specific logic like for specific client ip addresses or hostnames to return the pool with generic  host servers and not the one with LTM Virtual servers:

 

https://community.f5.com/t5/technical-forum/gtm-irule-to-set-the-pool-based-on-which-gtm-is-responding-to/td-p/109187

 

https://clouddocs.f5.com/api/irules/DNS_REQUEST.html

 

SMilanic's avatar
SMilanic
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May 13, 2022

Hi, Nikoolayy1,

thank you for your reply! It seems that "Generic Host" server type offers the options I need. I will look into it. Thanks!

 

  • Nikoolayy1's avatar
    Nikoolayy1
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    May 14, 2022

    I hope that it is the solution you are searching for. After you have tested, you can share with us so we can close this post.