diff --git a/checker/collect.go b/checker/collect.go
index 2b0fa74..c3892b6 100644
--- a/checker/collect.go
+++ b/checker/collect.go
@@ -23,9 +23,13 @@ package checker
 
 import (
 	"context"
+	"crypto/sha256"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"net"
+	"sort"
+	"strings"
 	"time"
 
 	probing "github.com/prometheus-community/pro-bing"
@@ -96,6 +100,31 @@ func (p *pingProvider) Collect(ctx context.Context, opts sdk.CheckerOptions) (an
 	return data, nil
 }
 
+// ShareKey implements sdk.ObservationSharer. A ping result depends only on the
+// set of target addresses and the probe count, never on which domain or service
+// the addresses belong to. Returning a stable key derived from those inputs lets
+// the host mutualise a single ICMP probe across every target (of the same user)
+// that points at the same address set, instead of re-pinging once per record.
+//
+// The evaluation thresholds (warningRTT, criticalRTT, …) are intentionally
+// excluded: they only affect how the shared observation is judged, not the data
+// collected. Inputs that cannot be resolved yield "" so the host falls back to
+// the default per-target caching.
+func (p *pingProvider) ShareKey(opts sdk.CheckerOptions) (string, error) {
+	addresses, err := resolveAddresses(opts)
+	if err != nil {
+		return "", nil
+	}
+
+	sorted := append([]string(nil), addresses...)
+	sort.Strings(sorted)
+
+	count := sdk.GetIntOption(opts, "count", 5)
+
+	h := sha256.Sum256(fmt.Appendf(nil, "%d|%s", count, strings.Join(sorted, ",")))
+	return "ping:" + hex.EncodeToString(h[:8]), nil
+}
+
 // resolveAddresses extracts target IP addresses from the options.
 func resolveAddresses(opts sdk.CheckerOptions) ([]string, error) {
 	// Direct addresses (from HTTP server).
diff --git a/checker/collect_test.go b/checker/collect_test.go
index 6a33bc5..e91cf9f 100644
--- a/checker/collect_test.go
+++ b/checker/collect_test.go
@@ -119,3 +119,59 @@ func TestIpsFromServiceEmpty(t *testing.T) {
 		t.Errorf("expected 0 ips, got %v", ips)
 	}
 }
+
+func TestShareKeyStableRegardlessOfOrder(t *testing.T) {
+	p := &pingProvider{}
+	a, err := p.ShareKey(sdk.CheckerOptions{"addresses": []string{"1.1.1.1", "2.2.2.2"}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	b, err := p.ShareKey(sdk.CheckerOptions{"addresses": []string{"2.2.2.2", "1.1.1.1"}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if a == "" {
+		t.Fatal("expected a non-empty share key")
+	}
+	if a != b {
+		t.Errorf("share key must not depend on address order: %q != %q", a, b)
+	}
+}
+
+func TestShareKeyDiffersByAddress(t *testing.T) {
+	p := &pingProvider{}
+	a, _ := p.ShareKey(sdk.CheckerOptions{"address": "1.1.1.1"})
+	b, _ := p.ShareKey(sdk.CheckerOptions{"address": "2.2.2.2"})
+	if a == b {
+		t.Errorf("different addresses must yield different share keys, both %q", a)
+	}
+}
+
+func TestShareKeyDiffersByCount(t *testing.T) {
+	p := &pingProvider{}
+	a, _ := p.ShareKey(sdk.CheckerOptions{"address": "1.1.1.1", "count": float64(5)})
+	b, _ := p.ShareKey(sdk.CheckerOptions{"address": "1.1.1.1", "count": float64(10)})
+	if a == b {
+		t.Errorf("different probe counts must yield different share keys, both %q", a)
+	}
+}
+
+func TestShareKeyIgnoresEvaluationThresholds(t *testing.T) {
+	p := &pingProvider{}
+	a, _ := p.ShareKey(sdk.CheckerOptions{"address": "1.1.1.1", "warningRTT": float64(100)})
+	b, _ := p.ShareKey(sdk.CheckerOptions{"address": "1.1.1.1", "warningRTT": float64(250)})
+	if a != b {
+		t.Errorf("evaluation thresholds must not affect the share key: %q != %q", a, b)
+	}
+}
+
+func TestShareKeyEmptyWhenUnresolvable(t *testing.T) {
+	p := &pingProvider{}
+	sk, err := p.ShareKey(sdk.CheckerOptions{})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if sk != "" {
+		t.Errorf("expected empty share key (per-target fallback), got %q", sk)
+	}
+}
diff --git a/go.mod b/go.mod
index 5714a0b..49e4d9c 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module git.happydns.org/checker-ping
 go 1.25.0
 
 require (
-	git.happydns.org/checker-sdk-go v1.5.0
+	git.happydns.org/checker-sdk-go v1.11.0
 	git.happydns.org/happyDomain v0.7.0
 	github.com/miekg/dns v1.1.72
 	github.com/prometheus-community/pro-bing v0.8.0
diff --git a/go.sum b/go.sum
index c1ed874..7ffcf8c 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,5 @@
-git.happydns.org/checker-sdk-go v1.5.0 h1:5uD5Cm6xJ+lwnhbJ09iCXGHbYS9zRh+Yh0NeBHkAPBY=
-git.happydns.org/checker-sdk-go v1.5.0/go.mod h1:aNAcfYFfbhvH9kJhE0Njp5GX0dQbxdRB0rJ0KvSC5nI=
+git.happydns.org/checker-sdk-go v1.11.0 h1:+hs8OpcgvRMAoWyfqxih/Q0KYYUI1R8oFxO4RKioMLk=
+git.happydns.org/checker-sdk-go v1.11.0/go.mod h1:aNAcfYFfbhvH9kJhE0Njp5GX0dQbxdRB0rJ0KvSC5nI=
 git.happydns.org/happyDomain v0.7.0 h1:NV82/NbcSeRm0+IUZqaK3Vu9Ovl5+vv4AigUJZMdwws=
 git.happydns.org/happyDomain v0.7.0/go.mod h1:5tgkmqFE65kK359rY49V++49wgZ0gco+Gh9X6tbL+bY=
 github.com/bytedance/gopkg v0.1.3 h1:TPBSwH8RsouGCBcMBktLt1AymVo2TVsBVCY4b6TnZ/M=