diff --git a/lib/Mail/SPF/Record.pm b/lib/Mail/SPF/Record.pm
index 1cb1f1b..0aad3c7 100644
--- a/lib/Mail/SPF/Record.pm
+++ b/lib/Mail/SPF/Record.pm
@@ -411,11 +411,16 @@ sub eval {
                     foreach my $dom ( @include_domains ) {
                       my $packet;
                       if(not exists $inc_domain_cname{$dom}) {
-                        $packet = $server->dns_lookup($dom, 'CNAME');
+                        # This CNAME check is auxiliary; a DNS failure here must
+                        # not turn an otherwise valid SPF evaluation into a
+                        # temperror, so treat any lookup error as "no CNAME".
+                        eval { $packet = $server->dns_lookup($dom, 'CNAME'); };
+                        next if $@;
                         $inc_domain_cname{$dom} = $packet->{answer}[0]->{cname}->{name};
                       }
                       if(defined $inc_domain_cname{$dom}) {
-                        if(grep /^$inc_domain_cname{$dom}$/, @include_domains) {
+                        (my $cname = $inc_domain_cname{$dom}) =~ s/\.$//;
+                        if(grep { lc($_) eq lc($cname) } @include_domains) {
                           $server->throw_result('fail', $request,
                                       'referencing the same TXT record through multiple CNAME aliases is not permitted');
                         }