diff --git a/jaeger-core/src/main/java/com/uber/jaeger/Tracer.java b/jaeger-core/src/main/java/com/uber/jaeger/Tracer.java
index f77cbdb3c..7a5f2144b 100644
--- a/jaeger-core/src/main/java/com/uber/jaeger/Tracer.java
+++ b/jaeger-core/src/main/java/com/uber/jaeger/Tracer.java
@@ -17,6 +17,8 @@
 import com.uber.jaeger.baggage.BaggageRestrictionManager;
 import com.uber.jaeger.baggage.BaggageSetter;
 import com.uber.jaeger.baggage.DefaultBaggageRestrictionManager;
+import com.uber.jaeger.exceptions.EmptyIpException;
+import com.uber.jaeger.exceptions.NotFourOctetsException;
 import com.uber.jaeger.exceptions.UnsupportedFormatException;
 import com.uber.jaeger.metrics.Metrics;
 import com.uber.jaeger.metrics.MetricsFactory;
@@ -98,16 +100,29 @@ private Tracer(
     this.version = loadVersion();
 
     tags.put(Constants.JAEGER_CLIENT_VERSION_TAG_KEY, this.version);
-    String hostname = getHostName();
-    if (hostname != null) {
-      tags.put(Constants.TRACER_HOSTNAME_TAG_KEY, hostname);
+    if (tags.get(Constants.TRACER_HOSTNAME_TAG_KEY) == null) {
+      String hostname = getHostName();
+      if (hostname != null) {
+        tags.put(Constants.TRACER_HOSTNAME_TAG_KEY, hostname);
+      }
     }
-    int ipv4 ;
-    try {
-      tags.put(Constants.TRACER_IP_TAG_KEY, InetAddress.getLocalHost().getHostAddress());
-      ipv4 = Utils.ipToInt(Inet4Address.getLocalHost().getHostAddress());
-    } catch (UnknownHostException e) {
-      ipv4 = 0;
+    int ipv4;
+    Object ipTag = tags.get(Constants.TRACER_IP_TAG_KEY);
+    if (ipTag == null) {
+      try {
+        tags.put(Constants.TRACER_IP_TAG_KEY, InetAddress.getLocalHost().getHostAddress());
+        ipv4 = Utils.ipToInt(Inet4Address.getLocalHost().getHostAddress());
+      } catch (UnknownHostException e) {
+        ipv4 = 0;
+      }
+    } else {
+      try {
+        ipv4 = Utils.ipToInt(ipTag.toString());
+      } catch (EmptyIpException e) {
+        ipv4 = 0;
+      } catch (NotFourOctetsException e) {
+        ipv4 = 0;
+      }
     }
     this.ipv4 = ipv4;
     this.tags = Collections.unmodifiableMap(tags);
diff --git a/jaeger-core/src/test/java/com/uber/jaeger/TracerTagsTest.java b/jaeger-core/src/test/java/com/uber/jaeger/TracerTagsTest.java
index e2a03d425..249ca340e 100644
--- a/jaeger-core/src/test/java/com/uber/jaeger/TracerTagsTest.java
+++ b/jaeger-core/src/test/java/com/uber/jaeger/TracerTagsTest.java
@@ -18,6 +18,9 @@
 
 import com.uber.jaeger.reporters.InMemoryReporter;
 import com.uber.jaeger.samplers.ConstSampler;
+import com.uber.jaeger.utils.Utils;
+import java.net.Inet4Address;
+import java.net.InetAddress;
 import org.junit.Test;
 
 public class TracerTagsTest {
@@ -38,4 +41,52 @@ public void testTracerTags() throws Exception {
     assertEquals(true, span.getTags().containsKey("sampler.param"));
     assertEquals(false, span.getTags().containsKey("tracer.tag.str"));
   }
+
+  @Test
+  public void testDefaultHostTags() throws Exception {
+    InMemoryReporter spanReporter = new InMemoryReporter();
+    Tracer tracer = new Tracer.Builder("x")
+        .withReporter(spanReporter)
+        .build();
+    assertEquals(tracer.getHostName(), tracer.tags().get(Constants.TRACER_HOSTNAME_TAG_KEY));
+    assertEquals(InetAddress.getLocalHost().getHostAddress(), tracer.tags().get(Constants.TRACER_IP_TAG_KEY));
+    assertEquals(Utils.ipToInt(Inet4Address.getLocalHost().getHostAddress()), tracer.getIpv4());
+  }
+
+  @Test
+  public void testDeclaredHostTags() throws Exception {
+    InMemoryReporter spanReporter = new InMemoryReporter();
+    String hostname = "myhost";
+    String ip = "1.1.1.1";
+    Tracer tracer = new Tracer.Builder("x")
+        .withReporter(spanReporter)
+        .withTag(Constants.TRACER_HOSTNAME_TAG_KEY, hostname)
+        .withTag(Constants.TRACER_IP_TAG_KEY, ip)
+        .build();
+    assertEquals(hostname, tracer.tags().get(Constants.TRACER_HOSTNAME_TAG_KEY));
+    assertEquals(ip, tracer.tags().get(Constants.TRACER_IP_TAG_KEY));
+    assertEquals(Utils.ipToInt(ip), tracer.getIpv4());
+  }
+
+  @Test
+  public void testEmptyDeclaredIpTag() throws Exception {
+    InMemoryReporter spanReporter = new InMemoryReporter();
+    String ip = "";
+    Tracer tracer = new Tracer.Builder("x")
+            .withReporter(spanReporter)
+            .withTag(Constants.TRACER_IP_TAG_KEY, ip)
+            .build();
+    assertEquals(0, tracer.getIpv4());
+  }
+
+  @Test
+  public void testShortDeclaredIpTag() throws Exception {
+    InMemoryReporter spanReporter = new InMemoryReporter();
+    String ip = ":19";
+    Tracer tracer = new Tracer.Builder("x")
+            .withReporter(spanReporter)
+            .withTag(Constants.TRACER_IP_TAG_KEY, ip)
+            .build();
+    assertEquals(0, tracer.getIpv4());
+  }
 }