diff --git a/type-challenges/ip.ts b/type-challenges/ip.ts
new file mode 100644
index 0000000..19af52e
--- /dev/null
+++ b/type-challenges/ip.ts
@@ -0,0 +1,63 @@
+type Split<S extends string, D extends string> = S extends ''
+  ? []
+  : S extends `${infer T}${D}${infer U}`
+    ? [T, ...Split<U, D>]
+    : [S];
+
+type UnwrapNumbers<T extends string | string[] | number | number[]> = T extends number | number[]
+  ? T
+  : T extends string
+    ? T extends `${infer N extends number}`
+      ? N
+      : never
+    : T extends [infer H extends string, ...infer T extends string[]]
+      ? UnwrapNumbers<H> extends never
+        ? never
+        : [UnwrapNumbers<H>, ...UnwrapNumbers<T>]
+      : [];
+
+type IPv4Octets = [number, number, number, number];
+
+type IPv4<CIDR extends string> = Split<CIDR, '/'> extends [
+  infer IP extends string,
+  infer SUBNET extends string,
+]
+  ? UnwrapNumbers<Split<IP, '.'>> extends infer OCTETS
+    ? OCTETS extends never
+      ? never
+      : OCTETS extends IPv4Octets
+        ? UnwrapNumbers<SUBNET> extends never
+          ? never
+          : CIDR
+        : never
+    : never
+  : never;
+
+type IPv6<CIDR extends string> = Split<CIDR, '/'> extends [
+  infer IP extends string,
+  infer SUBNET extends string,
+]
+  ? Split<IP, ':'> extends string[]
+    ? UnwrapNumbers<SUBNET> extends never
+      ? never
+      : CIDR
+    : never
+  : never;
+
+type Test_1 = IPv4<'0.0.0.0/0'>;
+type Test_2 = IPv4<'255.255.255.255/32'>;
+type Test_3 = IPv4<'127.0.0.0.1/32'>;
+type Test_4 = IPv4<'a'>;
+type Test_5 = IPv4<'1.1.1.a/32'>;
+type Test_6 = IPv4<'1.1.1.1'>;
+type Test_7 = IPv4<'1.1.1.1/'>;
+type Test_8 = IPv4<'1.1.1.1/a'>;
+
+type Test_9 = IPv6<'::/0'>;
+type Test_10 = IPv6<'ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff/128'>;
+type Test_11 = IPv6<'::1/128'>;
+type Test_12 = IPv6<'a'>;
+type Test_13 = IPv6<'1:1:1:1:1:1:1:1/128'>;
+type Test_14 = IPv6<'1:1:1:1:1:1:1:1'>;
+type Test_15 = IPv6<'1:1:1:1:1:1:1:1/'>;
+type Test_16 = IPv6<'1:1:1:1:1:1:1:1/a'>;