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