Or ( ... without grep, either OS-native nor Perl ...and definitely not to deprecate either suggestion above... ) you could go with a pair of arrays, this way:

#!/usr/bin/perl -w
use 5.016;
use strict;

# 1089209.pl

my @int_descriptions;            # OP suggests the seeker knows how to
+ obtain the array
                                 # so, here's a test case without anno
+ying the router 
@int_descriptions = (
    'foo.baz 12.247.62.7 20140608:1629',
    'royal.com 1.11.617.251 20140608:1457',
    'harvard.edu 1.1.217.0 20140608:1454',
    'smithbarney.fin 195.7.168.2 20140608:1454',
    'pomono.edu 93.16.124.5',
    'yale.edu 58.3.179.6',
    'etc.org 9.11.14.0 20140608:1320',
    );

open my $fh, '<', 'foo1089209.txt' or die "Can't open file for read, $
+!";

my @foo = <$fh>;

for my $foo(@foo) {
    chomp $foo;
    say " *** Testing for matches to \$foo: $foo ***";
    for (@int_descriptions) {
        my $int = qr/$_/;
        if ( $int =~ /$foo/ ) {
            say "\t \$foo: $foo found in \$int: $int";
        }
    }
    # next;
}
[download]

where foo1089209.txt looks like this:

my test file foo.bar
pomona.edu
wesleyan.edu
harvard.edu
yale.edu
mit.edu
oberline.edu
foo.com
bar.org
smithbarney.fin
ebay.co
ebay.com
[download]

Which give you, as output:

 *** Testing for matches to $foo: my test file foo.bar ***
 *** Testing for matches to $foo: pomona.edu ***
 *** Testing for matches to $foo: wesleyan.edu ***
 *** Testing for matches to $foo: harvard.edu ***
         $foo: harvard.edu found in $int: (?^u:harvard.edu 1.1.217.0 2
+0140608:1454)
 *** Testing for matches to $foo: yale.edu ***
         $foo: yale.edu found in $int: (?^u:yale.edu 58.3.179.6)
 *** Testing for matches to $foo: mit.edu ***
 *** Testing for matches to $foo: oberline.edu ***
 *** Testing for matches to $foo: foo.com ***
 *** Testing for matches to $foo: bar.org ***
 *** Testing for matches to $foo: smithbarney.fin ***
         $foo: smithbarney.fin found in $int: (?^u:smithbarney.fin 195
+.7.168.2 20140608:1454)
 *** Testing for matches to $foo: ebay.co ***
 *** Testing for matches to $foo: ebay.com ***
[download]

But -- that's not the most elegant of solutions.