diff --git a/net/dns/manager.go b/net/dns/manager.go
index 6810d5a6b..14e297408 100644
--- a/net/dns/manager.go
+++ b/net/dns/manager.go
@@ -262,6 +262,18 @@ func (m *Manager) compileConfig(cfg Config) (rcfg resolver.Config, ocfg OSConfig
 		// config is empty, then we need to fallback to SplitDNS mode.
 		ocfg.MatchDomains = cfg.matchDomains()
 	} else {
+		// On iOS only (for now), check if all route names point to resources inside the tailnet.
+		// If so, we can set those names as MatchDomains to enable a split DNS configuration
+		// which will help preserve battery life.
+		// Because on iOS MatchDomains must equal SearchDomains, we cannot do this when
+		// we have any Routes outside the tailnet. Otherwise when app connectors are enabled,
+		// a query for 'work-laptop' might lead to search domain expansion, resolving
+		// as 'work-laptop.aws.com' for example.
+		if runtime.GOOS == "ios" && rcfg.RoutesRequireNoCustomResolvers() {
+			for r := range rcfg.Routes {
+				ocfg.MatchDomains = append(ocfg.MatchDomains, r)
+			}
+		}
 		var defaultRoutes []*dnstype.Resolver
 		for _, ip := range baseCfg.Nameservers {
 			defaultRoutes = append(defaultRoutes, &dnstype.Resolver{Addr: ip.String()})
diff --git a/net/dns/resolver/tsdns.go b/net/dns/resolver/tsdns.go
index c44565ee1..dd0504baf 100644
--- a/net/dns/resolver/tsdns.go
+++ b/net/dns/resolver/tsdns.go
@@ -175,6 +175,25 @@ func WriteRoutes(w *bufio.Writer, routes map[dnsname.FQDN][]*dnstype.Resolver) {
 	}
 }
 
+// RoutesRequireNoCustomResolvers returns true if this resolver.Config only contains routes
+// that do not specify a set of custom resolver(s), i.e. they can be resolved by the local
+// upstream DNS resolver.
+func (c *Config) RoutesRequireNoCustomResolvers() bool {
+	for route, resolvers := range c.Routes {
+		if route.WithoutTrailingDot() == "ts.net" {
+			// Ignore the "ts.net" route here. It always specifies the corp resolvers but
+			// its presence is not an issue, as ts.net will be a search domain.
+			continue
+		}
+		if len(resolvers) != 0 {
+			// Found a route with custom resolvers.
+			return false
+		}
+	}
+	// No routes other than ts.net have specified one or more resolvers.
+	return true
+}
+
 // Resolver is a DNS resolver for nodes on the Tailscale network,
 // associating them with domain names of the form <mynode>.<mydomain>.<root>.
 // If it is asked to resolve a domain that is not of that form,
diff --git a/net/dns/resolver/tsdns_test.go b/net/dns/resolver/tsdns_test.go
index a0f625b20..fb33b49a8 100644
--- a/net/dns/resolver/tsdns_test.go
+++ b/net/dns/resolver/tsdns_test.go
@@ -243,6 +243,43 @@ func mustIP(str string) netip.Addr {
 	return ip
 }
 
+func TestRoutesRequireNoCustomResolvers(t *testing.T) {
+	tests := []struct {
+		name     string
+		config   Config
+		expected bool
+	}{
+		{"noRoutes", Config{Routes: map[dnsname.FQDN][]*dnstype.Resolver{}}, true},
+		{"onlyDefault", Config{Routes: map[dnsname.FQDN][]*dnstype.Resolver{
+			"ts.net.": {
+				{},
+			},
+		}}, true},
+		{"oneOther", Config{Routes: map[dnsname.FQDN][]*dnstype.Resolver{
+			"example.com.": {
+				{},
+			},
+		}}, false},
+		{"defaultAndOneOther", Config{Routes: map[dnsname.FQDN][]*dnstype.Resolver{
+			"ts.net.": {
+				{},
+			},
+			"example.com.": {
+				{},
+			},
+		}}, false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := tt.config.RoutesRequireNoCustomResolvers()
+			if result != tt.expected {
+				t.Errorf("result = %v; want %v", result, tt.expected)
+			}
+		})
+	}
+}
+
 func TestRDNSNameToIPv4(t *testing.T) {
 	tests := []struct {
 		name   string