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awan_m's avatar
awan_m
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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 www.xyz.com cache default_resolver_cache
tmsh delete ltm dns cache records msg qname www.xyz.com cache default_resolver_cache
 
Any Suggestions 
Thanks 
 
 
 
application delivery

4 Replies

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  • Paulius's avatar
    Paulius
    Icon for MVP rankMVP
    Jul 14, 2023

    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
      awan_m
      Icon for Cirrus rankCirrus
      Jul 14, 2023

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

      • Paulius's avatar
        Paulius
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        Jul 14, 2023

        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.

  • mplaksin0's avatar
    mplaksin0
    Icon for Cirrus rankCirrus
    Jul 14, 2023

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