dns_retransmit_interval

This directive is meaningful only when you use the internal DNS implementation (the default).

This directive is the initial retransmission interval for unacknowledged DNS queries. Each time Squid retransmits a DNS query, it's sent to the next DNS server in the list. If none of the servers answer, Squid starts at the top of the list again and doubles the retransmit interval.

dns_retransmit_interval time-specification

dns_retransmit_interval 5 seconds

dns_retransmit_interval 10 seconds