Others have given explanation, but I thought that I'd add that Math::BigInt will give the answer that you desire

perl -MMath::BigInt -le '
 $i=new Math::BigInt "4294967296";
 $j=new Math::BigInt "4294967295";
 print $i->as_hex();
 print $j->as_hex();
 print $i->band($j)->as_hex()'
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0x100000000
0xffffffff
0x0
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