diff --git a/vsock_proxy/src/dns.rs b/vsock_proxy/src/dns.rs
index 01f86213..fb0e2e7a 100644
--- a/vsock_proxy/src/dns.rs
+++ b/vsock_proxy/src/dns.rs
@@ -59,3 +59,86 @@ pub fn resolve_single(addr: &str, ip_addr_type: IpAddrType) -> VsockProxyResult<
     // We already know that rresults containt at least one item.
     Ok(rresults.first().unwrap().clone())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use ctor::ctor;
+    use std::sync::Once;
+    use std::env;
+
+    static TEST_INIT: Once = Once::new();
+
+    static mut INVALID_TEST_DOMAIN: &'static str = "invalid-domain";
+    static mut IPV4_ONLY_TEST_DOMAIN: &'static str = "v4.ipv6test.app";
+    static mut IPV6_ONLY_TEST_DOMAIN: &'static str = "v6.ipv6test.app";
+    static mut DUAL_IP_TEST_DOMAIN: &'static str = "ipv6test.app";
+
+    #[test]
+    #[ctor]
+    fn init() {
+        // *** To use nonlocal domain names, set TEST_NONLOCAL_DOMAINS variable. ***
+        // *** TEST_NONLOCAL_DOMAINS=1 cargo test                                ***
+        TEST_INIT.call_once(|| {
+            if env::var_os("TEST_NONLOCAL_DOMAINS").is_none() {
+                eprintln!("[warn] dns: using 'localhost' for testing.");
+                unsafe {
+                    IPV4_ONLY_TEST_DOMAIN = "localhost";
+                    IPV6_ONLY_TEST_DOMAIN = "::1";
+                    DUAL_IP_TEST_DOMAIN = "localhost";
+                }
+            }
+        });
+    }
+
+    #[test]
+    fn test_resolve_valid_domain() {
+        let domain = unsafe { IPV4_ONLY_TEST_DOMAIN };
+        let rresults = resolve(domain, IpAddrType::IPAddrMixed).unwrap();
+        assert!(!rresults.is_empty());
+    }
+
+    #[test]
+    fn test_resolve_valid_dual_ip_domain() {
+        let domain = unsafe { DUAL_IP_TEST_DOMAIN };
+        let rresults = resolve(domain, IpAddrType::IPAddrMixed).unwrap();
+        assert!(!rresults.is_empty());
+    }
+
+    #[test]
+    fn test_resolve_invalid_domain() {
+        let domain = unsafe { INVALID_TEST_DOMAIN };
+        let rresults = resolve(domain, IpAddrType::IPAddrMixed);
+        assert!(rresults.is_err() && rresults.err().unwrap().eq("DNS lookup failed!"));
+    }
+
+    #[test]
+    fn test_resolve_ipv4_only() {
+        let domain = unsafe { IPV4_ONLY_TEST_DOMAIN };
+        let rresults = resolve(domain, IpAddrType::IPAddrV4Only).unwrap();
+        assert!(rresults.iter().all(|item| item.ip.is_ipv4()));
+    }
+
+    #[test]
+    fn test_resolve_ipv6_only() {
+        let domain = unsafe { IPV6_ONLY_TEST_DOMAIN };
+        let rresults = resolve(domain, IpAddrType::IPAddrV6Only).unwrap();
+        assert!(rresults.iter().all(|item| item.ip.is_ipv6()));
+    }
+
+    #[test]
+    fn test_resolve_no_accepted_ip() {
+        let domain = unsafe { IPV4_ONLY_TEST_DOMAIN };
+        let rresults = resolve(domain, IpAddrType::IPAddrV6Only);
+        assert!(rresults.is_err() && rresults.err().unwrap().eq("No accepted IP was found."));
+    }
+
+    #[test]
+    fn test_resolve_single_address() {
+        let domain = unsafe { IPV4_ONLY_TEST_DOMAIN };
+        let rresult = resolve_single(domain, IpAddrType::IPAddrMixed).unwrap();
+        assert!(rresult.ip.is_ipv4());
+        assert!(rresult.ttl != 0);
+    }
+}