diff --git a/Tun/Punchnet/DNS/DNSCloudClient.swift b/Tun/Punchnet/DNS/DNSCloudClient.swift
index 58040ac..ac4539a 100644
--- a/Tun/Punchnet/DNS/DNSCloudClient.swift
+++ b/Tun/Punchnet/DNS/DNSCloudClient.swift
@@ -42,16 +42,16 @@ final class DNSCloudClient {
         self.packetContinuation = packetPair.continuation
     }
 
-    private static func makeEndpointHost(address: String) -> NWEndpoint.Host {
-        if let ipv4Address = IPv4Address(address) {
+    private static func makeEndpointHost(address ip: String) -> NWEndpoint.Host {
+        if let ipv4Address = IPv4Address(ip) {
             return .ipv4(ipv4Address)
         }
 
-        if let ipv6Address = IPv6Address(address) {
+        if let ipv6Address = IPv6Address(ip) {
             return .ipv6(ipv6Address)
         }
 
-        return .name(address, nil)
+        preconditionFailure("invalid DNS cloud server IP: \(ip)")
     }
     
     func start() {
diff --git a/Tun/Punchnet/DNS/DNSLocalClient.swift b/Tun/Punchnet/DNS/DNSLocalClient.swift
index 749d8b0..05cd0e0 100644
--- a/Tun/Punchnet/DNS/DNSLocalClient.swift
+++ b/Tun/Punchnet/DNS/DNSLocalClient.swift
@@ -44,7 +44,7 @@ actor DNSLocalClient {
     private var nextTransactionID: UInt16 = 1
     
     init(host: String) {
-        self.dnsServerEndpoint = .hostPort(host: NWEndpoint.Host(host), port: 53)
+        self.dnsServerEndpoint = .hostPort(host: Self.makeEndpointHost(ip: host), port: 53)
         
         let (stream, continuation) = AsyncThrowingStream.makeStream(of: Data.self, bufferingPolicy: .bufferingNewest(256))
         self.packetFlow = stream
@@ -54,6 +54,18 @@ actor DNSLocalClient {
             SDLLogger.log("[DNSLocalClient] packetFlow terminated: \(termination)")
         }
     }
+
+    private static func makeEndpointHost(ip: String) -> NWEndpoint.Host {
+        if let ipv4Address = IPv4Address(ip) {
+            return .ipv4(ipv4Address)
+        }
+
+        if let ipv6Address = IPv6Address(ip) {
+            return .ipv6(ipv6Address)
+        }
+
+        preconditionFailure("invalid public DNS server IP: \(ip)")
+    }
     
     func start() {
         guard self.state == .idle else {
diff --git a/Tun/Punchnet/SDLIPV6AssistClient.swift b/Tun/Punchnet/SDLIPV6AssistClient.swift
index 66d7fa9..13d7d02 100644
--- a/Tun/Punchnet/SDLIPV6AssistClient.swift
+++ b/Tun/Punchnet/SDLIPV6AssistClient.swift
@@ -33,10 +33,12 @@ actor SDLIPV6AssistClient {
     private var pendingRequests: [UInt32: PendingRequest] = [:]
 
     init?(assistServerInfo: SDLV6Info) {
-        guard assistServerInfo.port <= UInt32(UInt16.max), let host = SDLUtil.ipv6DataToString(assistServerInfo.v6) else {
+        guard assistServerInfo.port <= UInt32(UInt16.max),
+              let host = SDLUtil.ipv6DataToString(assistServerInfo.v6),
+              let address = IPv6Address(host) else {
             return nil
         }
-        self.assistServerAddress = .hostPort(host: NWEndpoint.Host(host), port: NWEndpoint.Port(integerLiteral: UInt16(assistServerInfo.port)))
+        self.assistServerAddress = .hostPort(host: .ipv6(address), port: NWEndpoint.Port(integerLiteral: UInt16(assistServerInfo.port)))
     }
     
     func start() {
diff --git a/Tun/Punchnet/SDLUtil.swift b/Tun/Punchnet/SDLUtil.swift
index fc8f244..526838e 100644
--- a/Tun/Punchnet/SDLUtil.swift
+++ b/Tun/Punchnet/SDLUtil.swift
@@ -7,7 +7,6 @@
 
 import Foundation
 import SystemConfiguration
-import Network
 import Darwin
 
 struct SDLUtil {
@@ -111,31 +110,4 @@ struct SDLUtil {
         }
         return results
     }
-    
-    // 域名解析
-    static func resolveHostname(host: String) async -> String? {
-        let endpoint = NWEndpoint.hostPort(host: NWEndpoint.Host(host), port: 53)
-        let parameters = NWParameters.udp
-        // 即使还没正式开始，也加上这个，确保不会被残留的旧 utun 路由卡死
-        parameters.prohibitedInterfaceTypes = [.other]
-        
-        let connection = NWConnection(to: endpoint, using: parameters)
-        
-        return await withCheckedContinuation { continuation in
-            connection.stateUpdateHandler = { state in
-                if case .ready = state {
-                    if let path = connection.currentPath,
-                       case .hostPort(let resolvedHost, _) = path.remoteEndpoint {
-                        let ip = String(describing: resolvedHost)
-                        continuation.resume(returning: ip)
-                        connection.cancel()
-                    }
-                } else if case .failed = state {
-                    continuation.resume(returning: nil)
-                }
-            }
-            connection.start(queue: .global())
-        }
-    }
-
 }
diff --git a/Tun/Punchnet/Super/SDLSuperClient.swift b/Tun/Punchnet/Super/SDLSuperClient.swift
index 86b1acd..aab0530 100644
--- a/Tun/Punchnet/Super/SDLSuperClient.swift
+++ b/Tun/Punchnet/Super/SDLSuperClient.swift
@@ -97,16 +97,16 @@ actor SDLSuperClient {
         self.connection = connection
     }
 
-    private static func makeEndpointHost(address: String) -> NWEndpoint.Host {
-        if let ipv4Address = IPv4Address(address) {
+    private static func makeEndpointHost(address ip: String) -> NWEndpoint.Host {
+        if let ipv4Address = IPv4Address(ip) {
             return .ipv4(ipv4Address)
         }
 
-        if let ipv6Address = IPv6Address(address) {
+        if let ipv6Address = IPv6Address(ip) {
             return .ipv6(ipv6Address)
         }
 
-        return .name(address, nil)
+        preconditionFailure("invalid super server IP: \(ip)")
     }
     
     private func handleConnectionState(state: NWConnection.State) {