diff --git a/minidns-android21/src/main/java/org/minidns/dnsserverlookup/android21/AndroidUsingLinkProperties.java b/minidns-android21/src/main/java/org/minidns/dnsserverlookup/android21/AndroidUsingLinkProperties.java
index d5f7a49d..05f995f1 100644
--- a/minidns-android21/src/main/java/org/minidns/dnsserverlookup/android21/AndroidUsingLinkProperties.java
+++ b/minidns-android21/src/main/java/org/minidns/dnsserverlookup/android21/AndroidUsingLinkProperties.java
@@ -24,6 +24,7 @@
 import org.minidns.DnsClient;
 import org.minidns.dnsserverlookup.AbstractDnsServerLookupMechanism;
 import org.minidns.dnsserverlookup.AndroidUsingExec;
+import org.minidns.dnsserverlookup.IPPortPair;
 
 /**
  * A DNS server lookup mechanism using Android's Link Properties method available on Android API 21 or higher. Use
@@ -61,7 +62,7 @@ public boolean isAvailable() {
 
     @Override
     @TargetApi(21)
-    public List<String> getDnsServerAddresses() {
+    public List<IPPortPair> getDnsServerAddresses() {
         Network[] networks = connectivityManager.getAllNetworks();
         if (networks == null) {
             return null;
@@ -86,7 +87,7 @@ public List<String> getDnsServerAddresses() {
             return null;
         }
 
-        return servers;
+        return stringCollectionToListOfIPPortPairs(servers);
     }
 
     @TargetApi(Build.VERSION_CODES.LOLLIPOP)
diff --git a/minidns-client/src/main/java/org/minidns/DnsClient.java b/minidns-client/src/main/java/org/minidns/DnsClient.java
index 3dff40fe..8874bf58 100644
--- a/minidns-client/src/main/java/org/minidns/DnsClient.java
+++ b/minidns-client/src/main/java/org/minidns/DnsClient.java
@@ -18,6 +18,7 @@
 import org.minidns.dnsserverlookup.AndroidUsingExec;
 import org.minidns.dnsserverlookup.AndroidUsingReflection;
 import org.minidns.dnsserverlookup.DnsServerLookupMechanism;
+import org.minidns.dnsserverlookup.IPPortPair;
 import org.minidns.dnsserverlookup.UnixUsingEtcResolvConf;
 import org.minidns.util.CollectionsUtil;
 import org.minidns.util.ExceptionCallback;
@@ -99,8 +100,8 @@ protected DnsMessage.Builder newQuestion(DnsMessage.Builder message) {
         return message;
     }
 
-    private List<InetAddress> getServerAddresses() {
-        List<InetAddress> dnsServerAddresses = findDnsAddresses();
+    private List<UpstreamDNSServer> getServerAddresses() {
+        List<UpstreamDNSServer> dnsServerAddresses = findDnsAddresses();
 
         InetAddress[] selectedHardcodedDnsServerAddresses = new InetAddress[2];
         if (useHardcodedDnsServers) {
@@ -126,7 +127,7 @@ private List<InetAddress> getServerAddresses() {
         }
         for (InetAddress selectedHardcodedDnsServerAddress : selectedHardcodedDnsServerAddresses) {
             if (selectedHardcodedDnsServerAddress == null) continue;
-            dnsServerAddresses.add(selectedHardcodedDnsServerAddress);
+            dnsServerAddresses.add(new UpstreamDNSServer(selectedHardcodedDnsServerAddress, IPPortPair.DEFAULT_PORT));
         }
 
         return dnsServerAddresses;
@@ -145,17 +146,17 @@ public DnsQueryResult query(DnsMessage.Builder queryBuilder) throws IOException
             return dnsQueryResult;
         }
 
-        List<InetAddress> dnsServerAddresses = getServerAddresses();
+        List<UpstreamDNSServer> dnsServerAddresses = getServerAddresses();
 
         List<IOException> ioExceptions = new ArrayList<>(dnsServerAddresses.size());
-        for (InetAddress dns : dnsServerAddresses) {
-            if (nonRaServers.contains(dns)) {
+        for (UpstreamDNSServer dns : dnsServerAddresses) {
+            if (nonRaServers.contains(dns.getServer())) {
                 LOGGER.finer("Skipping " + dns + " because it was marked as \"recursion not available\"");
                 continue;
             }
 
             try {
-                dnsQueryResult = query(q, dns);
+                dnsQueryResult = query(q, dns.getServer(), dns.getPort());
             } catch (IOException ioe) {
                 ioExceptions.add(ioe);
                 continue;
@@ -163,7 +164,7 @@ public DnsQueryResult query(DnsMessage.Builder queryBuilder) throws IOException
 
             DnsMessage responseMessage = dnsQueryResult.response;
             if (!responseMessage.recursionAvailable) {
-                boolean newRaServer = nonRaServers.add(dns);
+                boolean newRaServer = nonRaServers.add(dns.getServer());
                 if (newRaServer) {
                     LOGGER.warning("The DNS server " + dns
                             + " returned a response without the \"recursion available\" (RA) flag set. This likely indicates a misconfiguration because the server is not suitable for DNS resolution");
@@ -215,16 +216,16 @@ protected MiniDnsFuture<DnsQueryResult, IOException> queryAsync(DnsMessage.Build
             return MiniDnsFuture.from(responseMessage);
         }
 
-        final List<InetAddress> dnsServerAddresses = getServerAddresses();
+        final List<UpstreamDNSServer> dnsServerAddresses = getServerAddresses();
 
         final InternalMiniDnsFuture<DnsQueryResult, IOException> future = new InternalMiniDnsFuture<>();
         final List<IOException> exceptions = Collections.synchronizedList(new ArrayList<IOException>(dnsServerAddresses.size()));
 
         // Filter loop.
-        Iterator<InetAddress> it = dnsServerAddresses.iterator();
+        Iterator<UpstreamDNSServer> it = dnsServerAddresses.iterator();
         while (it.hasNext()) {
-            InetAddress dns = it.next();
-            if (nonRaServers.contains(dns)) {
+            UpstreamDNSServer dns = it.next();
+            if (nonRaServers.contains(dns.getServer())) {
                 it.remove();
                 LOGGER.finer("Skipping " + dns + " because it was marked as \"recursion not available\"");
                 continue;
@@ -233,7 +234,7 @@ protected MiniDnsFuture<DnsQueryResult, IOException> queryAsync(DnsMessage.Build
 
         List<MiniDnsFuture<DnsQueryResult, IOException>> futures = new ArrayList<>(dnsServerAddresses.size());
         // "Main" loop.
-        for (InetAddress dns : dnsServerAddresses) {
+        for (UpstreamDNSServer dns : dnsServerAddresses) {
             if (future.isDone()) {
                 for (MiniDnsFuture<DnsQueryResult, IOException> futureToCancel : futures) {
                     futureToCancel.cancel(true);
@@ -241,7 +242,7 @@ protected MiniDnsFuture<DnsQueryResult, IOException> queryAsync(DnsMessage.Build
                 break;
             }
 
-            MiniDnsFuture<DnsQueryResult, IOException> f = queryAsync(q, dns);
+            MiniDnsFuture<DnsQueryResult, IOException> f = queryAsync(q, dns.getServer(), dns.getPort());
             f.onSuccess(new SuccessCallback<DnsQueryResult>() {
                 @Override
                 public void onSuccess(DnsQueryResult result) {
@@ -272,8 +273,8 @@ public void processException(IOException exception) {
      *
      * @return A list of DNS server IP addresses configured for this system.
      */
-    public static List<String> findDNS() {
-        List<String> res = null;
+    public static List<IPPortPair> findDNS() {
+        List<IPPortPair> res = null;
         for (DnsServerLookupMechanism mechanism : LOOKUP_MECHANISMS) {
             res = mechanism.getDnsServerAddresses();
             if (res == null) {
@@ -289,14 +290,14 @@ public static List<String> findDNS() {
             // especially a valid DNS name is returned, as this would cause the following String to InetAddress conversation using
             // getByName(String) to cause a DNS lookup, which would be performed outside of the realm of MiniDNS and therefore also outside
             // of its DNSSEC guarantees.
-            Iterator<String> it = res.iterator();
+            Iterator<IPPortPair> it = res.iterator();
             while (it.hasNext()) {
-                String potentialDnsServer = it.next();
-                if (!InetAddressUtil.isIpAddress(potentialDnsServer)) {
+                IPPortPair potentialDnsServer = it.next();
+                if (!InetAddressUtil.isIpAddress(potentialDnsServer.getIp())) {
                     LOGGER.warning("The DNS server lookup mechanism '" + mechanism.getName()
                             + "' returned an invalid non-IP address result: '" + potentialDnsServer + "'");
                     it.remove();
-                } else if (blacklistedDnsServers.contains(potentialDnsServer)) {
+                } else if (blacklistedDnsServers.contains(potentialDnsServer.getIp())) {
                     LOGGER.fine("The DNS server lookup mechanism '" + mechanism.getName()
                     + "' returned a blacklisted result: '" + potentialDnsServer + "'");
                     it.remove();
@@ -325,9 +326,9 @@ public static List<String> findDNS() {
      * @return A list of DNS server addresses.
      * @see #findDNS()
      */
-    public static List<InetAddress> findDnsAddresses() {
+    public static List<UpstreamDNSServer> findDnsAddresses() {
         // The findDNS() method contract guarantees that only IP addresses will be returned.
-        List<String> res = findDNS();
+        List<IPPortPair> res = findDNS();
 
         if (res == null) {
             return new ArrayList<>();
@@ -335,8 +336,8 @@ public static List<InetAddress> findDnsAddresses() {
 
         final IpVersionSetting setting = DEFAULT_IP_VERSION_SETTING;
 
-        List<Inet4Address> ipv4DnsServer = null;
-        List<Inet6Address> ipv6DnsServer = null;
+        List<UpstreamDNSServer> ipv4DnsServer = null;
+        List<UpstreamDNSServer> ipv6DnsServer = null;
         if (setting.v4) {
             ipv4DnsServer = new ArrayList<>(res.size());
         }
@@ -344,17 +345,18 @@ public static List<InetAddress> findDnsAddresses() {
             ipv6DnsServer = new ArrayList<>(res.size());
         }
 
-        for (String dnsServerString : res) {
+        for (IPPortPair dnsServer : res) {
             // The following invariant must hold: "dnsServerString is a IP address". Therefore findDNS() must only return a List of Strings
             // representing IP addresses. Otherwise the following call of getByName(String) may perform a DNS lookup without MiniDNS being
             // involved. Something we want to avoid.
-            assert (InetAddressUtil.isIpAddress(dnsServerString));
+            assert (InetAddressUtil.isIpAddress(dnsServer.getIp()));
+            assert (dnsServer.getPort() >= 1 && dnsServer.getPort() <= 65535);
 
             InetAddress dnsServerAddress;
             try {
-                dnsServerAddress = InetAddress.getByName(dnsServerString);
+                dnsServerAddress = InetAddress.getByName(dnsServer.getIp());
             } catch (UnknownHostException e) {
-                LOGGER.log(Level.SEVERE, "Could not transform '" + dnsServerString + "' to InetAddress", e);
+                LOGGER.log(Level.SEVERE, "Could not transform '" + dnsServer + "' to InetAddress", e);
                 continue;
             }
             if (dnsServerAddress instanceof Inet4Address) {
@@ -362,19 +364,19 @@ public static List<InetAddress> findDnsAddresses() {
                     continue;
                 }
                 Inet4Address ipv4DnsServerAddress = (Inet4Address) dnsServerAddress;
-                ipv4DnsServer.add(ipv4DnsServerAddress);
+                ipv4DnsServer.add(new UpstreamDNSServer(ipv4DnsServerAddress, dnsServer.getPort()));
             } else if (dnsServerAddress instanceof Inet6Address) {
                 if (!setting.v6) {
                     continue;
                 }
                 Inet6Address ipv6DnsServerAddress = (Inet6Address) dnsServerAddress;
-                ipv6DnsServer.add(ipv6DnsServerAddress);
+                ipv6DnsServer.add(new UpstreamDNSServer(ipv6DnsServerAddress, dnsServer.getPort()));
             } else {
                 throw new AssertionError("The address '" + dnsServerAddress + "' is neither of type Inet(4|6)Address");
             }
         }
 
-        List<InetAddress> dnsServers = new LinkedList<>();
+        List<UpstreamDNSServer> dnsServers = new LinkedList<>();
 
         switch (setting) {
         case v4v6:
@@ -462,4 +464,22 @@ public InetAddress getRandomHardcodedIpv4DnsServer() {
     public InetAddress getRandomHarcodedIpv6DnsServer() {
         return CollectionsUtil.getRandomFrom(STATIC_IPV6_DNS_SERVERS, insecureRandom);
     }
+
+    public static class UpstreamDNSServer {
+        private InetAddress server;
+        private int port;
+
+        public UpstreamDNSServer(InetAddress server, int port) {
+            this.server = server;
+            this.port = port;
+        }
+
+        public InetAddress getServer() {
+            return server;
+        }
+
+        public int getPort() {
+            return port;
+        }
+    }
 }
diff --git a/minidns-client/src/main/java/org/minidns/dnsserverlookup/AbstractDnsServerLookupMechanism.java b/minidns-client/src/main/java/org/minidns/dnsserverlookup/AbstractDnsServerLookupMechanism.java
index 49920cbd..660c24c5 100644
--- a/minidns-client/src/main/java/org/minidns/dnsserverlookup/AbstractDnsServerLookupMechanism.java
+++ b/minidns-client/src/main/java/org/minidns/dnsserverlookup/AbstractDnsServerLookupMechanism.java
@@ -44,7 +44,7 @@ public final int compareTo(DnsServerLookupMechanism other) {
     }
 
     @Override
-    public abstract List<String> getDnsServerAddresses();
+    public abstract List<IPPortPair> getDnsServerAddresses();
 
     protected static List<String> toListOfStrings(Collection<? extends InetAddress> inetAddresses) {
         List<String> result = new ArrayList<>(inetAddresses.size());
@@ -54,4 +54,21 @@ protected static List<String> toListOfStrings(Collection<? extends InetAddress>
         }
         return result;
     }
+
+    protected static List<IPPortPair> inetAddressCollectionToListOfIPPortPairs(Collection<? extends InetAddress> inetAddresses){
+        List<IPPortPair> result = new ArrayList<>(inetAddresses.size());
+        for (InetAddress inetAddress : inetAddresses) {
+            String address = inetAddress.getHostAddress();
+            result.add(new IPPortPair(address, IPPortPair.DEFAULT_PORT));
+        }
+        return result;
+    }
+
+    protected static List<IPPortPair> stringCollectionToListOfIPPortPairs(Collection<String> serverAddresses){
+        List<IPPortPair> result = new ArrayList<>(serverAddresses.size());
+        for (String address : serverAddresses) {
+            result.add(new IPPortPair(address, IPPortPair.DEFAULT_PORT));
+        }
+        return result;
+    }
 }
diff --git a/minidns-client/src/main/java/org/minidns/dnsserverlookup/AndroidUsingExec.java b/minidns-client/src/main/java/org/minidns/dnsserverlookup/AndroidUsingExec.java
index 023226d3..dae4565a 100644
--- a/minidns-client/src/main/java/org/minidns/dnsserverlookup/AndroidUsingExec.java
+++ b/minidns-client/src/main/java/org/minidns/dnsserverlookup/AndroidUsingExec.java
@@ -38,7 +38,7 @@ private AndroidUsingExec() {
     }
 
     @Override
-    public List<String> getDnsServerAddresses() {
+    public List<IPPortPair> getDnsServerAddresses() {
         try {
             Process process = Runtime.getRuntime().exec("getprop");
             InputStream inputStream = process.getInputStream();
@@ -48,7 +48,7 @@ public List<String> getDnsServerAddresses() {
             if (server.size() > 0) {
                 List<String> res = new ArrayList<>(server.size());
                 res.addAll(server);
-                return res;
+                return stringCollectionToListOfIPPortPairs(res);
             }
         } catch (IOException e) {
             LOGGER.log(Level.WARNING, "Exception in findDNSByExec", e);
diff --git a/minidns-client/src/main/java/org/minidns/dnsserverlookup/AndroidUsingReflection.java b/minidns-client/src/main/java/org/minidns/dnsserverlookup/AndroidUsingReflection.java
index b9822497..a9869ac6 100644
--- a/minidns-client/src/main/java/org/minidns/dnsserverlookup/AndroidUsingReflection.java
+++ b/minidns-client/src/main/java/org/minidns/dnsserverlookup/AndroidUsingReflection.java
@@ -31,7 +31,7 @@ protected AndroidUsingReflection() {
     }
 
     @Override
-    public List<String> getDnsServerAddresses() {
+    public List<IPPortPair> getDnsServerAddresses() {
         try {
             Class<?> SystemProperties =
                     Class.forName("android.os.SystemProperties");
@@ -63,7 +63,7 @@ public List<String> getDnsServerAddresses() {
             }
 
             if (servers.size() > 0) {
-                return servers;
+                return stringCollectionToListOfIPPortPairs(servers);
             }
         } catch (Exception e) {
             // we might trigger some problems this way
diff --git a/minidns-client/src/main/java/org/minidns/dnsserverlookup/DnsServerLookupMechanism.java b/minidns-client/src/main/java/org/minidns/dnsserverlookup/DnsServerLookupMechanism.java
index d26fd08b..67c76aac 100644
--- a/minidns-client/src/main/java/org/minidns/dnsserverlookup/DnsServerLookupMechanism.java
+++ b/minidns-client/src/main/java/org/minidns/dnsserverlookup/DnsServerLookupMechanism.java
@@ -27,8 +27,8 @@ public interface DnsServerLookupMechanism extends Comparable<DnsServerLookupMech
      * when using {@link org.minidns.DnsClient#findDNS()}.
      * </p>
      *
-     * @return a List of Strings presenting hopefully IP addresses.
+     * @return a List of IPPortPairs presenting hopefully IP addresses with their respective ports.
      */
-    public List<String> getDnsServerAddresses();
+    public List<IPPortPair> getDnsServerAddresses();
 
 }
diff --git a/minidns-client/src/main/java/org/minidns/dnsserverlookup/IPPortPair.java b/minidns-client/src/main/java/org/minidns/dnsserverlookup/IPPortPair.java
new file mode 100644
index 00000000..908a4fb8
--- /dev/null
+++ b/minidns-client/src/main/java/org/minidns/dnsserverlookup/IPPortPair.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2015-2018 the original author or authors
+ *
+ * This software is licensed under the Apache License, Version 2.0,
+ * the GNU Lesser General Public License version 2 or later ("LGPL")
+ * and the WTFPL.
+ * You may choose either license to govern your use of this software only
+ * upon the condition that you accept all of the terms of either
+ * the Apache License 2.0, the LGPL 2.1+ or the WTFPL.
+ */
+package org.minidns.dnsserverlookup;
+
+import java.io.Serializable;
+
+public class IPPortPair implements Serializable {
+    private static final long serialVersionUID = 7354713072355023750L;
+    public static final int DEFAULT_PORT = 53;
+    private int port;
+    private String ip;
+
+    public IPPortPair(String ip) {
+        this(ip, DEFAULT_PORT);
+    }
+
+    public IPPortPair(String ip, int port) {
+        this.port = port;
+        this.ip = ip;
+    }
+
+    public int getPort() {
+        return port;
+    }
+
+    public String getIp() {
+        return ip;
+    }
+}
diff --git a/minidns-client/src/main/java/org/minidns/dnsserverlookup/UnixUsingEtcResolvConf.java b/minidns-client/src/main/java/org/minidns/dnsserverlookup/UnixUsingEtcResolvConf.java
index 59fac40e..96a24c7c 100644
--- a/minidns-client/src/main/java/org/minidns/dnsserverlookup/UnixUsingEtcResolvConf.java
+++ b/minidns-client/src/main/java/org/minidns/dnsserverlookup/UnixUsingEtcResolvConf.java
@@ -34,7 +34,7 @@ public class UnixUsingEtcResolvConf extends AbstractDnsServerLookupMechanism {
     private static final String RESOLV_CONF_FILE = "/etc/resolv.conf";
     private static final Pattern NAMESERVER_PATTERN = Pattern.compile("^nameserver\\s+(.*)$");
 
-    private static List<String> cached;
+    private static List<IPPortPair> cached;
     private static long lastModified;
 
     private UnixUsingEtcResolvConf() {
@@ -42,7 +42,7 @@ private UnixUsingEtcResolvConf() {
     }
 
     @Override
-    public List<String> getDnsServerAddresses() {
+    public List<IPPortPair> getDnsServerAddresses() {
         File file = new File(RESOLV_CONF_FILE);
         if (!file.exists()) {
             // Not very unixoid systems
@@ -81,7 +81,7 @@ public List<String> getDnsServerAddresses() {
             return null;
         }
 
-        cached = servers;
+        cached = stringCollectionToListOfIPPortPairs(servers);
         lastModified = currentLastModified;
 
         return cached;
diff --git a/minidns-client/src/test/java/org/minidns/DnsClientTest.java b/minidns-client/src/test/java/org/minidns/DnsClientTest.java
index 31c4fa7d..7664d5d5 100644
--- a/minidns-client/src/test/java/org/minidns/DnsClientTest.java
+++ b/minidns-client/src/test/java/org/minidns/DnsClientTest.java
@@ -18,6 +18,7 @@
 import org.minidns.dnsserverlookup.AbstractDnsServerLookupMechanism;
 import org.minidns.dnsserverlookup.AndroidUsingExec;
 import org.minidns.dnsserverlookup.AndroidUsingReflection;
+import org.minidns.dnsserverlookup.IPPortPair;
 import org.minidns.dnsserverlookup.DnsServerLookupMechanism;
 import org.minidns.record.A;
 import org.minidns.record.Record.TYPE;
@@ -69,7 +70,7 @@ public boolean isAvailable() {
             return true;
         }
         @Override
-        public List<String> getDnsServerAddresses() {
+        public List<IPPortPair> getDnsServerAddresses() {
             return null;
         }
     }