That looks like a hash of arrays:

my @domains = qw( thisun.com thatun.net );

my %time_of_ip;
$time_of_ip{ @domains } = [];
for (@domains) {
    push @{$time_of_ip{$_}}, timings($_);
}

sub timings {
    my $ip = shift;
    #whatever
}
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After Compline,
Zaxo