diff --git a/zonedb.rkt b/zonedb.rkt
index 0644a7b..58f5be4 100644
--- a/zonedb.rkt
+++ b/zonedb.rkt
@@ -179,7 +179,15 @@
 ;; rr-set->list : SetOf<RR> -> ListOf<RR>
 ;; Like set->list, but places all CNAME records first.
 ;; This is apparently to work around bugs in old versions of BIND?
+;;
 ;; TODO: Perhaps the CNAMEs even need to be in topologically-sorted order?
+;; http://homepage.ntlworld.com./jonathan.deboynepollard/FGA/dns-response-taxonomy.html
+;; has this to say on this topic:
+;;   "A content DNS server following the algorithm in § 4.3.2 of RFC
+;;    1034 will insert this chain in first-to-last order in the
+;;    response. The response parsing code in most resolving proxy DNS
+;;    servers and DNS client libraries expects this order. However,
+;;    the actual text of RFC 1034 itself does not guarantee it."
 (define (rr-set->list rrs)
   (append (set->list (filter-by-type rrs 'cname))
 	  (set->list (set-filter (lambda (rr) (not (eqv? (rr-type rr) 'cname))) rrs))))