diff --git a/ex/key2ds/key2ds.go b/ex/key2ds/key2ds.go
deleted file mode 100644
index b58d990b..00000000
--- a/ex/key2ds/key2ds.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package main
-
-// Print the DNSKEY records of a domain as DS records
-// Twist with all the other tools that can do this. Do
-// this directly from the internet.
-// (c) Miek Gieben - 2011
-import (
-	"fmt"
-	"github.com/miekg/dns"
-	"os"
-)
-
-func main() {
-	conf, err := dns.ClientConfigFromFile("/etc/resolv.conf")
-	if len(os.Args) != 2 || err != nil {
-		fmt.Printf("%s DOMAIN\n", os.Args[0])
-		os.Exit(1)
-	}
-	m := new(dns.Msg)
-	m.SetQuestion(dns.Fqdn(os.Args[1]), dns.TypeDNSKEY)
-	m.SetEdns0(2048, true)
-
-	c := new(dns.Client)
-	r, _ := c.Exchange(m, conf.Servers[0]+":"+conf.Port)
-	if r == nil {
-		fmt.Printf("*** no answer received for %s\n", os.Args[1])
-		os.Exit(1)
-	}
-
-	if r.Rcode != dns.RcodeSuccess {
-		fmt.Printf(" *** invalid answer name %s after DNSKEY query for %s\n", os.Args[1], os.Args[1])
-		os.Exit(1)
-	}
-	for _, k := range r.Answer {
-		if key, ok := k.(*dns.RR_DNSKEY); ok {
-			key.Hdr.Ttl = 0
-			for _, alg := range []int{dns.SHA1, dns.SHA256, dns.SHA384} {
-				ds := key.ToDS(alg)
-				fmt.Printf("%v; %d\n", ds, key.Flags)
-			}
-		}
-	}
-}
diff --git a/example_test.go b/example_test.go
index ab6bd00b..507fff67 100644
--- a/example_test.go
+++ b/example_test.go
@@ -24,3 +24,30 @@ func ExampleRR_MX() {
 		}
 	}
 }
+
+// Retrieve the DNSKEY records of a zone and convert them
+// to DS records for SHA1, SHA256 and SHA384.
+func ExampleToDs(zone string) {
+	config, _ := ClientConfigFromFile("/etc/resolv.conf")
+	c := new(Client)
+	m := new(Msg)
+	if zone == "" {
+		zone = "miek.nl"
+	}
+	m.SetQuestion(Fqdn(zone), TypeDNSKEY)
+	m.SetEdns0(4096, true)
+	r, err := c.Exchange(m, config.Servers[0]+":"+config.Port)
+	if err != nil {
+		return
+	}
+	if r.Rcode != RcodeSuccess {
+		return
+	}
+	for _, k := range r.Answer {
+		if key, ok := k.(*RR_DNSKEY); ok {
+			for _, alg := range []int{SHA1, SHA256, SHA384} {
+				fmt.Printf("%s; %d\n", key.ToDS(alg).String(), key.Flags)
+			}
+		}
+	}
+}