diff --git a/youngjin.han/ipv6/ipv6.org b/youngjin.han/ipv6/ipv6.org
index 982f221..c72bae3 100644
--- a/youngjin.han/ipv6/ipv6.org
+++ b/youngjin.han/ipv6/ipv6.org
@@ -1,3 +1,6 @@
+* 2020-07-24
+** note
+   - none
 * 2020-07-22
 ** note
     - none
diff --git a/youngjin.han/ipv6/source/randomnet.py b/youngjin.han/ipv6/source/randomnet.py
new file mode 100644
index 0000000..2cc835e
--- /dev/null
+++ b/youngjin.han/ipv6/source/randomnet.py
@@ -0,0 +1,59 @@
+# from sys import argv
+import argparse
+import ipaddress
+import random
+
+# script, prefix = argv
+
+def main(ipv6net_list, size_list):
+    """
+    메인 함수
+    """
+    if 2 == len(ipv6net_list):
+        ipv6net_src =  ipaddress.IPv6Interface(ipv6net_list[0])
+        size = ipv6net_list[1]
+        print('Input : {}'.format(ipv6net_src))
+        print('Size : {}'.format(size))
+    elif 2 > len(ipv6net_list):
+        ipv6net_src =  ipaddress.IPv6Interface(ipv6net_list[0])
+        size = size_list
+        print('Input : {}'.format(ipv6net_list))
+        print('Size : {}'.format(size))
+    else:
+        ipv6net_src = []
+        size = size_list
+        print('Please, Read Help')
+
+    ipv6_rand = 0
+    size_rand = int(size)-int(str(ipv6net_src)[str(ipv6net_src).find('/')+1:])
+    while size_rand != 0:
+        if 16 <= size_rand:
+            ipv6_rand = ipv6_rand << 16
+            ipv6_rand += random.randint(0, (2**16)-1)
+            size_rand -= 16
+        else:
+            ipv6_rand = ipv6_rand << size_rand
+            ipv6_rand += random.randint(0, (2**size_rand)-1)
+            size_rand = 0
+
+#    print('{}'.format(ipaddress.IPv6Network((ipv6net_src))))
+#    print('{}'.format(str(ipaddress.IPv6Address((ipv6_rand<<(128-int(size)))))+'/'+size))
+#    print('{}'.format(int(size)-int(str(ipv6net_src)[str(ipv6net_src).find('/')+1:])))
+    print('Output : {}'.format(str(ipaddress.IPv6Address(int(ipv6net_src)+(ipv6_rand <<(128 - int(size)))))+'/'+size))
+
+def get_arguments():
+    """
+    argument를 파싱해서 가져옴
+    """
+    parser = argparse.ArgumentParser()
+    parser.add_argument('ipv6net', nargs='+', help='Example) 2001:db8::/40 or 2001:db8::/40 64', type=str)
+    parser.add_argument('--size', nargs='?', help='Example) 64...0', default='48', type=str)
+
+    ipv6net_list = parser.parse_args().ipv6net
+    size_list = parser.parse_args().size
+
+    return ipv6net_list, size_list
+
+if __name__ == '__main__':
+    ipv6net_list, size_list = get_arguments()
+    main(ipv6net_list, size_list)
diff --git a/youngjin.han/learning-node02-2020.org b/youngjin.han/learning-node02-2020.org
index 0e90c5f..69a7f6f 100644
--- a/youngjin.han/learning-node02-2020.org
+++ b/youngjin.han/learning-node02-2020.org
@@ -1,3 +1,24 @@
+* 2020-07-24
+*** IPv6 #2: Generating IPv6 networks
+**** DONE Lecture content
+     CLOSED: [2020-07-30 목 00:43]
+    - Objective/Problem that we are trying to solve:
+      - You got one bigger prefix (the one that you get as a
+        parameter) and you want to create a random subnetwork in it
+    - Create a random /48 network within a prefix
+      - Create a python script named *randomnet.py* that accepts 1
+        parameter: *prefix*
+      - The prefix must be an IPv6 network
+      - The netmask of the prefix should be /48 or smaller (/48.../0)
+      - Prefixes to be used for testing:
+        - 2001:db8::/48
+        - 2001:db8::/40
+        - 2001:db8::/32
+        - fd00::/8
+      - Possible output:
+        - 2001:db8:1231::/48
+    - Optional
+      - Allow to specify second parameter that gives the size of the subnetwork
 * 2020-07-22
 *** IPv6 #1: IPv6 address uniqueness
 **** DONE Lecture content