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nickamon's avatar
nickamon
Icon for Nimbostratus rankNimbostratus
Jul 29, 2024

Big IP FQDN Pool Member Resolution from /etc/hosts

Hi,   I've added entries to the Big IP /etc/hosts file to map custom FQDNs to IP addresses (in an attempt to workaround the restriction of having LTM nodes with the same address).  I then created a...
BIG-IP
LTM
pool member
Paulius's avatar
Paulius
Icon for MVP rankMVP
Jul 30, 2024

You shouldn't have to modify the /etc/hosts file because the F5 has a built in feature in the GUI which I believe is outlined in the following article.

https://my.f5.com/manage/s/article/K13206

I do not believe this addition changes what an FQDN resolves to in a pool and looks like it is always resolved by a DNS query which doesn't check the hosts file. We attempted this previously at the company that I work for and it only seemed to effect none tmsh communication.

  • nickamon's avatar
    nickamon
    Icon for Nimbostratus rankNimbostratus
    Jul 30, 2024

    Thanks Paulius , I am aware of the GUI option but I'm adding this via automation and the entries only need to exist temporarily (I understand that they will be overwritten by updates from the GUI).  Disappointedly, I think you are correct, the FQDN pool members are only resolved via a DNS query and don't reference /etc/hosts at all.

    Back to the drawing board with this.

    Thanks!

    • boneyard's avatar
      boneyard
      Icon for MVP rankMVP
      Jul 30, 2024

      the article mentioned exactly states that indeed:

      Note: Beginning in version 11.6.0, the BIG-IP system uses DNS to resolve host names for nodes and pool members that are identified with fully qualified domain names (FQDNs) and does not consult the /etc/hosts file.

      why do you need multiple nodes with the same IP address?