diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4816958c..a042957b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -116,8 +116,7 @@ install(TARGETS skyr-url
         ARCHIVE DESTINATION lib
         LIBRARY DESTINATION lib)
 
-
-        install(EXPORT ${PROJECT_NAME}-targets
+install(EXPORT ${PROJECT_NAME}-targets
         DESTINATION "${CMAKE_INSTALL_DATADIR}/cmake/${PROJECT_NAME}"
         NAMESPACE skyr::
         FILE "${PROJECT_NAME}-targets.cmake")
diff --git a/include/skyr/url.hpp b/include/skyr/url.hpp
index 69e5d457..8a25e3a6 100644
--- a/include/skyr/url.hpp
+++ b/include/skyr/url.hpp
@@ -19,6 +19,8 @@
 #include <skyr/url/url_record.hpp>
 #include <skyr/url/url_error.hpp>
 #include <skyr/url/url_search_parameters.hpp>
+#include <skyr/url/ipv4_address.hpp>
+#include <skyr/url/ipv6_address.hpp>
 #include <skyr/url/details/to_bytes.hpp>
 
 #if defined(SKYR_PLATFORM_MSVC)
@@ -364,6 +366,26 @@ class url {
   /// \returns An error on failure to parse the new URL
   tl::expected<void, std::error_code> set_hostname(string_view hostname);
 
+  /// Checks if the hostname is a valid IPv4 address
+  [[nodiscard]] bool is_ipv4_address() const;
+
+  /// Returns an optional ipv4_address value if the hostname is a
+  /// valid IPv4 address
+  [[nodiscard]] std::optional<skyr::ipv4_address> ipv4_address() const;
+
+  /// Checks if the hostname is a valid IPv6 address
+  [[nodiscard]] bool is_ipv6_address() const;
+
+  /// Returns an optional ipv6_address value if the hostname is a
+  /// valid IPv6 address
+  [[nodiscard]] std::optional<skyr::ipv6_address> ipv6_address() const;
+
+  /// Checks if the hostname is a valid domain name
+  [[nodiscard]] bool is_domain() const;
+
+  /// Checks if the hostname is a valid domain name
+  [[nodiscard]] bool is_opaque() const;
+
   /// Returns the [URL port](https://url.spec.whatwg.org/#dom-url-port)
   ///
   /// \returns The [URL port](https://url.spec.whatwg.org/#dom-url-port)
diff --git a/include/skyr/url/details/endianness.hpp b/include/skyr/url/details/endianness.hpp
new file mode 100644
index 00000000..f44b558e
--- /dev/null
+++ b/include/skyr/url/details/endianness.hpp
@@ -0,0 +1,42 @@
+// Copyright 2020 Glyn Matthews.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef SKYR_URL_ENDIANNESS_HPP
+#define SKYR_URL_ENDIANNESS_HPP
+
+#include <type_traits>
+#include <array>
+
+namespace skyr {
+inline namespace v1 {
+namespace details {
+inline bool is_big_endian() noexcept {
+  const auto word = 0x0001;
+  auto bytes = static_cast<const unsigned char *>(static_cast<const void *>(&word));
+  return bytes[0] != 0x01;
+}
+
+template <typename intT>
+inline intT swap_endianness(intT v, typename std::enable_if<std::is_integral<intT>::value>::type * = nullptr) noexcept {
+  constexpr auto byte_count = sizeof(v);
+  std::array<unsigned char, byte_count> bytes{};
+  for (auto i = 0UL; i < byte_count; ++i) {
+    bytes[i] = (v >> (i * 8));
+  }
+  return *static_cast<const intT *>(static_cast<const void *>(bytes.data()));
+}
+
+inline unsigned int to_network_byte_order(unsigned int v) noexcept {
+  return (is_big_endian()) ? v : swap_endianness(v);
+}
+
+inline unsigned int from_network_byte_order(unsigned int v) noexcept {
+  return (is_big_endian()) ? v : swap_endianness(v);
+}
+}  // namespace details
+}  // namespace v1
+}  // namespace skyr
+
+#endif //SKYR_URL_ENDIANNESS_HPP
diff --git a/src/url/ipv4_address.hpp b/include/skyr/url/ipv4_address.hpp
similarity index 74%
rename from src/url/ipv4_address.hpp
rename to include/skyr/url/ipv4_address.hpp
index ac285add..3cac1835 100644
--- a/src/url/ipv4_address.hpp
+++ b/include/skyr/url/ipv4_address.hpp
@@ -1,4 +1,4 @@
-// Copyright 2018 Glyn Matthews.
+// Copyright 2018-20 Glyn Matthews.
 // Distributed under the Boost Software License, Version 1.0.
 // (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
@@ -6,11 +6,13 @@
 #ifndef SKYR_IPV4_ADDRESS_INC
 #define SKYR_IPV4_ADDRESS_INC
 
+#include <array>
 #include <string>
 #include <string_view>
 #include <system_error>
 #include <optional>
 #include <tl/expected.hpp>
+#include <skyr/url/details/endianness.hpp>
 
 namespace skyr {
 inline namespace v1 {
@@ -45,12 +47,23 @@ class ipv4_address {
    /// Constructor
    /// \param address Sets the IPv4 address to `address`
   explicit ipv4_address(unsigned int address)
-      : address_(address) {}
+      : address_(details::to_network_byte_order(address)) {}
 
   /// The address value
   /// \returns The address value
   [[nodiscard]] unsigned int address() const noexcept {
-    return address_;
+    return details::from_network_byte_order(address_);
+  }
+
+  /// The address in bytes in network byte order
+  /// \returns The address in bytes
+  [[nodiscard]] std::array<unsigned char, 4> to_bytes() const noexcept {
+    return {{
+      static_cast<unsigned char>(address_ >> 24u),
+      static_cast<unsigned char>(address_ >> 16u),
+      static_cast<unsigned char>(address_ >>  8u),
+      static_cast<unsigned char>(address_ >>  0u)
+    }};
   }
 
   /// \returns The address as a string
diff --git a/src/url/ipv6_address.hpp b/include/skyr/url/ipv6_address.hpp
similarity index 70%
rename from src/url/ipv6_address.hpp
rename to include/skyr/url/ipv6_address.hpp
index 6731f23d..ce8bca08 100644
--- a/src/url/ipv6_address.hpp
+++ b/include/skyr/url/ipv6_address.hpp
@@ -1,4 +1,4 @@
-// Copyright 2018 Glyn Matthews.
+// Copyright 2018-20 Glyn Matthews.
 // Distributed under the Boost Software License, Version 1.0.
 // (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
@@ -13,6 +13,7 @@
 #include <iterator>
 #include <system_error>
 #include <tl/expected.hpp>
+#include <skyr/url/details/endianness.hpp>
 
 namespace skyr {
 inline namespace v1 {
@@ -42,8 +43,6 @@ class ipv6_address {
 
   std::array<unsigned short, 8> address_ = {0, 0, 0, 0, 0, 0, 0, 0};
 
-  using repr_type = decltype(address_);
-
  public:
 
   /// Constructor
@@ -51,10 +50,24 @@ class ipv6_address {
 
   /// Constructor
   /// \param address Sets the IPv6 address to `address`
-  explicit ipv6_address(std::array<unsigned short, 8> address)
-      : address_(address) {}
+  explicit ipv6_address(std::array<unsigned short, 8> address) {
+    for (auto i = 0UL; i < address.size(); ++i) {
+      address_[i] = details::to_network_byte_order(address[i]);
+    }
+  }
+
+  /// The address in bytes in network byte order
+  /// \returns The address in bytes
+  [[nodiscard]] std::array<unsigned char, 16> to_bytes() const noexcept {
+    std::array<unsigned char, 16> bytes{};
+    for (auto i = 0UL; i < address_.size(); ++i) {
+      bytes[i * 2    ] = static_cast<unsigned char>(address_[i] >> 8u);
+      bytes[i * 2 + 1] = static_cast<unsigned char>(address_[i]);
+    }
+    return bytes;
+  }
 
-   /// \returns The IPv4 address as a string
+   /// \returns The IPv6 address as a string
   [[nodiscard]] std::string to_string() const;
 
 };
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index d95925ed..fc85cbdc 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -16,9 +16,7 @@ set(skyr_SRCS
         url/url_parser_context.cpp
         url/url_record.cpp
         url/ipv4_address.cpp
-        url/ipv4_address.hpp
         url/ipv6_address.cpp
-        url/ipv6_address.hpp
         url/algorithms.hpp
         url/url_parse.cpp
         url/url_parse_impl.hpp
@@ -33,7 +31,6 @@ set(skyr_SRCS
 
         ${PROJECT_SOURCE_DIR}/include/skyr/config.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/version.hpp
-        ${PROJECT_SOURCE_DIR}/include/skyr/url/details/to_bytes.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/traits/string_traits.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/unicode/errors.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/unicode/core.hpp
@@ -48,10 +45,14 @@ set(skyr_SRCS
         ${PROJECT_SOURCE_DIR}/include/skyr/unicode/ranges/transforms/u32_transform.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/unicode/idna.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/unicode/domain.hpp
+        ${PROJECT_SOURCE_DIR}/include/skyr/url/details/to_bytes.hpp
+        ${PROJECT_SOURCE_DIR}/include/skyr/url/details/endianness.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/url/percent_encoding/errors.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/url/percent_encoding/percent_decode_range.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/url/percent_encoding/percent_encode_range.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/url/percent_encoding/percent_encoded_char.hpp
+        ${PROJECT_SOURCE_DIR}/include/skyr/url/ipv4_address.hpp
+        ${PROJECT_SOURCE_DIR}/include/skyr/url/ipv6_address.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/url/url_record.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/url/url_parse.hpp
         ${PROJECT_SOURCE_DIR}/include/skyr/url/url_serialize.hpp
@@ -82,6 +83,3 @@ target_include_directories(skyr-url
         $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
     PRIVATE
         ${PROJECT_SOURCE_DIR}/src)
-#
-##propagate sources to parent scope for one-lib-build
-#set(skyr_SRCS ${skyr_SRCS} PARENT_SCOPE)
diff --git a/src/url/ipv4_address.cpp b/src/url/ipv4_address.cpp
index f2b52542..598189f9 100644
--- a/src/url/ipv4_address.cpp
+++ b/src/url/ipv4_address.cpp
@@ -11,7 +11,7 @@
 #include <optional>
 #include <cstdlib>
 #include <cerrno>
-#include "ipv4_address.hpp"
+#include <skyr/url/ipv4_address.hpp>
 
 namespace skyr {
 inline namespace v1 {
diff --git a/src/url/ipv6_address.cpp b/src/url/ipv6_address.cpp
index 6083c96e..28fe06a6 100644
--- a/src/url/ipv6_address.cpp
+++ b/src/url/ipv6_address.cpp
@@ -1,4 +1,4 @@
-// Copyright 2018 Glyn Matthews.
+// Copyright 2018-20 Glyn Matthews.
 // Distributed under the Boost Software License, Version 1.0.
 // (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
@@ -10,7 +10,7 @@
 #include <locale>
 #include <algorithm>
 #include <optional>
-#include "ipv6_address.hpp"
+#include <skyr/url/ipv6_address.hpp>
 #include "algorithms.hpp"
 
 namespace skyr {
diff --git a/src/url/url.cpp b/src/url/url.cpp
index 333febe7..5336219c 100644
--- a/src/url/url.cpp
+++ b/src/url/url.cpp
@@ -188,6 +188,47 @@ tl::expected<void, std::error_code> url::set_hostname(string_view hostname) {
       });
 }
 
+bool url::is_ipv4_address() const {
+  return parse_ipv4_address(hostname()).has_value();
+}
+
+std::optional<skyr::ipv4_address> url::ipv4_address() const {
+  auto address = parse_ipv4_address(hostname());
+  return address.has_value() ? std::make_optional(address.value()) : std::nullopt;
+}
+
+bool url::is_ipv6_address() const {
+  if (!url_.host) {
+    return false;
+  }
+  auto view = std::string_view(url_.host.value());
+  if ((view.size() <= 2) || view.front() != '[' || view.back() != ']') {
+    return false;
+  }
+  return parse_ipv6_address(view.substr(1, view.size() - 2)).has_value();
+}
+
+std::optional<skyr::ipv6_address> url::ipv6_address() const {
+  if (!url_.host) {
+    return std::nullopt;
+  }
+  auto view = std::string_view(url_.host.value());
+  if ((view.size() <= 2) || view.front() != '[' || view.back() != ']') {
+    return std::nullopt;
+  }
+
+  auto address = parse_ipv6_address(view.substr(1, view.size() - 2));
+  return address.has_value() ? std::make_optional(address.value()) : std::nullopt;
+}
+
+bool url::is_domain() const {
+  return details::is_special(url_.scheme) && !hostname().empty() && !is_ipv4_address() && !is_ipv6_address();
+}
+
+bool url::is_opaque() const {
+  return !details::is_special(url_.scheme) && !hostname().empty();
+}
+
 url::string_type url::port() const {
   if (!url_.port) {
     return {};
diff --git a/src/url/url_parser_context.cpp b/src/url/url_parser_context.cpp
index bc92d93a..4411561f 100644
--- a/src/url/url_parser_context.cpp
+++ b/src/url/url_parser_context.cpp
@@ -17,8 +17,8 @@
 #include <skyr/url/percent_encoding/percent_encode_range.hpp>
 #include "url_parser_context.hpp"
 #include "url_schemes.hpp"
-#include "ipv4_address.hpp"
-#include "ipv6_address.hpp"
+#include "skyr/url/ipv4_address.hpp"
+#include "skyr/url/ipv6_address.hpp"
 #include "algorithms.hpp"
 
 namespace skyr {
diff --git a/tests/url/ipv4_address_tests.cpp b/tests/url/ipv4_address_tests.cpp
index 18b0dcb5..cb5f9583 100644
--- a/tests/url/ipv4_address_tests.cpp
+++ b/tests/url/ipv4_address_tests.cpp
@@ -5,7 +5,7 @@
 
 #define CATCH_CONFIG_MAIN
 #include <catch.hpp>
-#include "../../src/url/ipv4_address.hpp"
+#include <skyr/url/ipv4_address.hpp>
 
 TEST_CASE("ipv4 addresses", "[ipv4]") {
   using namespace std::string_literals;
@@ -46,6 +46,13 @@ TEST_CASE("ipv4 addresses", "[ipv4]") {
     CHECK(0x814ff5fc == instance.value().address());
   }
 
+  SECTION("parse_address_looks_short_test") {
+    const auto address = "129.79.245"s;
+    auto instance = skyr::parse_ipv4_address(address);
+    REQUIRE(instance);
+    CHECK(0x814f00f5 == instance.value().address());
+  }
+
   SECTION("parse_address_with_hex") {
     const auto address = "0x7f.0.0.0x7f"s;
     auto instance = skyr::parse_ipv4_address(address);
@@ -58,4 +65,17 @@ TEST_CASE("ipv4 addresses", "[ipv4]") {
     auto instance = skyr::parse_ipv4_address(address);
     REQUIRE_FALSE(instance);
   }
+
+  SECTION("loopback_as_bytes") {
+    auto instance = skyr::ipv4_address(0x7f000001);
+    std::array<unsigned char, 4> bytes{{0x7f, 0x00, 0x00, 0x01}};
+    CHECK(bytes == instance.to_bytes());
+  }
+
+  SECTION("parse_loopback_test_as_bytes") {
+    auto instance = skyr::parse_ipv4_address("127.0.0.1"s);
+    REQUIRE(instance);
+    std::array<unsigned char, 4> bytes{{0x7f, 0x00, 0x00, 0x01}};
+    CHECK(bytes == instance.value().to_bytes());
+  }
 }
diff --git a/tests/url/ipv6_address_tests.cpp b/tests/url/ipv6_address_tests.cpp
index 0c7aba90..4ad3c49a 100644
--- a/tests/url/ipv6_address_tests.cpp
+++ b/tests/url/ipv6_address_tests.cpp
@@ -5,7 +5,7 @@
 
 #define CATCH_CONFIG_MAIN
 #include <catch.hpp>
-#include "../../src/url/ipv6_address.hpp"
+#include <skyr/url/ipv6_address.hpp>
 
 TEST_CASE("ipv6_address_tests", "[ipv6]") {
   using namespace std::string_literals;
@@ -133,4 +133,14 @@ TEST_CASE("ipv6_address_tests", "[ipv6]") {
     REQUIRE(instance);
     CHECK("::ffff:c000:280" == instance.value().to_string());
   }
+
+  SECTION("loopback_test") {
+    auto address = std::array<unsigned short, 8>{{0, 0, 0, 0, 0, 0, 0, 1}};
+    auto instance = skyr::ipv6_address(address);
+    std::array<unsigned char, 16> bytes{
+      {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+      }};
+    CHECK(bytes == instance.to_bytes());
+  }
 }
diff --git a/tests/url/url_tests.cpp b/tests/url/url_tests.cpp
index 8f78fd3e..6ed9d524 100644
--- a/tests/url/url_tests.cpp
+++ b/tests/url/url_tests.cpp
@@ -168,6 +168,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://129.79.245.252/");
     CHECK("http:" == instance.protocol());
     CHECK("129.79.245.252" == instance.host());
+    CHECK(instance.is_ipv4_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -175,6 +176,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://127.0.0.1/");
     CHECK("http:" == instance.protocol());
     CHECK("127.0.0.1" == instance.host());
+    CHECK(instance.is_ipv4_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -182,6 +184,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[1080:0:0:0:8:800:200C:417A]/");
     CHECK("http:" == instance.protocol());
     CHECK("[1080::8:800:200c:417a]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -189,6 +192,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[2001:db8:85a3:8d3:1319:8a2e:370:7348]/");
     CHECK("http:" == instance.protocol());
     CHECK("[2001:db8:85a3:8d3:1319:8a2e:370:7348]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -196,6 +200,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[2001:db8:85a3:0:0:8a2e:370:7334]/");
     CHECK("http:" == instance.protocol());
     CHECK("[2001:db8:85a3::8a2e:370:7334]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -203,6 +208,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[2001:db8:85a3::8a2e:370:7334]/");
     CHECK("http:" == instance.protocol());
     CHECK("[2001:db8:85a3::8a2e:370:7334]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -210,6 +216,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[2001:0db8:0000:0000:0000:0000:1428:57ab]/");
     CHECK("http:" == instance.protocol());
     CHECK("[2001:db8::1428:57ab]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -217,6 +224,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[2001:0db8:0000:0000:0000::1428:57ab]/");
     CHECK("http:" == instance.protocol());
     CHECK("[2001:db8::1428:57ab]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -224,6 +232,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[2001:0db8:0:0:0:0:1428:57ab]/");
     CHECK("http:" == instance.protocol());
     CHECK("[2001:db8::1428:57ab]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -231,6 +240,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[2001:0db8:0:0::1428:57ab]/");
     CHECK("http:" == instance.protocol());
     CHECK("[2001:db8::1428:57ab]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -238,6 +248,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[2001:0db8::1428:57ab]/");
     CHECK("http:" == instance.protocol());
     CHECK("[2001:db8::1428:57ab]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -245,6 +256,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[2001:db8::1428:57ab]/");
     CHECK("http:" == instance.protocol());
     CHECK("[2001:db8::1428:57ab]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -252,6 +264,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[::ffff:0c22:384e]/");
     CHECK("http:" == instance.protocol());
     CHECK("[::ffff:c22:384e]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -259,6 +272,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[fe80::]/");
     CHECK("http:" == instance.protocol());
     CHECK("[fe80::]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -266,6 +280,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[::ffff:c000:280]/");
     CHECK("http:" == instance.protocol());
     CHECK("[::ffff:c000:280]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -273,6 +288,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[::1]/");
     CHECK("http:" == instance.protocol());
     CHECK("[::1]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -280,6 +296,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[0000:0000:0000:0000:0000:0000:0000:0001]/");
     CHECK("http:" == instance.protocol());
     CHECK("[::1]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -287,6 +304,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[::ffff:12.34.56.78]/");
     CHECK("http:" == instance.protocol());
     CHECK("[::ffff:c22:384e]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -294,6 +312,7 @@ TEST_CASE("url_tests", "[url]") {
     auto instance = skyr::url("http://[::ffff:192.0.2.128]/");
     CHECK("http:" == instance.protocol());
     CHECK("[::ffff:c000:280]" == instance.host());
+    CHECK(instance.is_ipv6_address());
     CHECK("/" == instance.pathname());
   }
 
@@ -569,8 +588,7 @@ TEST_CASE("url_tests", "[url]") {
     CHECK("?a=b&c=d" == instance.search());
   }
 
-  SECTION("domain_to_ascii_be_strict_issue_36")
-  {
+  SECTION("domain_to_ascii_be_strict_issue_36") {
     auto instance = skyr::url("https://+:80/vroot/");
     CHECK("https:" == instance.protocol());
     CHECK("+:80" == instance.host());
@@ -578,4 +596,52 @@ TEST_CASE("url_tests", "[url]") {
     CHECK("80" == instance.port());
     CHECK("/vroot/" == instance.pathname());
   }
+
+  SECTION("is_ipv4_accessor_like_short_ipv4_issue_51") {
+    auto instance = skyr::url("http://198.51.100/");
+    CHECK(instance.is_ipv4_address());
+    CHECK(!instance.is_ipv6_address());
+    CHECK(!instance.is_domain());
+    CHECK(!instance.is_opaque());
+  }
+
+  SECTION("is_ipv4_accessor_like_long_ipv4_issue_51") {
+    auto instance = skyr::url("http://198.51.100.0.255/");
+    CHECK(!instance.is_ipv4_address());
+    CHECK(!instance.is_ipv6_address());
+    CHECK(instance.is_domain());
+    CHECK(!instance.is_opaque());
+  }
+
+  SECTION("is_ipv4_accessor_like_short_ipv4_issue_51") {
+    auto instance = skyr::url("http://0x7f.0.0.0x7f/");
+    CHECK(instance.is_ipv4_address());
+    CHECK(!instance.is_ipv6_address());
+    CHECK(!instance.is_domain());
+    CHECK(!instance.is_opaque());
+  }
+
+  SECTION("is_domain_issue_51") {
+    auto instance = skyr::url("http://www.example.com/");
+    CHECK(!instance.is_ipv4_address());
+    CHECK(!instance.is_ipv6_address());
+    CHECK(instance.is_domain());
+    CHECK(!instance.is_opaque());
+  }
+
+  SECTION("is_opaque_issue_5") {
+    auto instance = skyr::url("git://example.com");
+    CHECK(!instance.is_ipv4_address());
+    CHECK(!instance.is_ipv6_address());
+    CHECK(!instance.is_domain());
+    CHECK(instance.is_opaque());
+  }
+
+  SECTION("is_opaque_ipv6_issue_5") {
+    auto instance = skyr::url("non-special://[1:2:0:0:5:0:0:0]/");
+    CHECK(!instance.is_ipv4_address());
+    CHECK(instance.is_ipv6_address());
+    CHECK(!instance.is_domain());
+    CHECK(instance.is_opaque());
+  }
 }