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awan_m's avatar
Icon for Cirrostratus rankCirrostratus
Jul 13, 2023

RESOLV::lookup not updating to new ip address

Hi - 

My irule is usong the resolv statement to resolve a name - 

set hostIP [lindex [RESOLV::lookup @$static::dns_vs inet -a $hostname] 0]
we are experiencing issue when a DNS record is updated - the resolver does not resolve to the new ip address
i tried clearing the cache aswell but that did not help .
tmsh delete ltm dns cache records rrset owner cache default_resolver_cache
tmsh delete ltm dns cache records msg qname cache default_resolver_cache
Any Suggestions 

4 Replies

  • awan_m Would you mind sharing the entire iRule that this resides in? Based on the information you have provided the DNS record should follow the TTL of the DNS record that was returned to it, so if your TTL for the record is lets say 5 hours then it could take up to 5 hours for the F5 to receive some other response.

    • awan_m's avatar
      Icon for Cirrostratus rankCirrostratus

      i understand the TTL part - but is there no way to clear cache and force a new resolution ?

      • Paulius's avatar
        Icon for MVP rankMVP

        awan_m You clear it the same way I believe you have been clearing it. I think the issue you are experiencing is that the cacheing NS still has the old record and not the new record and that is the issue you're running into. You should be able to double check this by logging into the CLI in bash and doing a "dig @<configured_dns_IP> <FQDN>" which will query the DNS server you have specified, which should be the same as the DNS server that the F5 has configured for DNS queries.

  • Check the TTL of the domain you're looking at. Check if using the dig command within the F5 CLI you receive the desired input.