First Digits to Identify Address Type
General | More Obvious | Type |
2000::/3 | Begins with 2 Begins with 3 |
Global Unicast Address |
fc00::/7* | Begins with fd | Unique Local Address |
fe80::/64 | Begins with fe80:0:0:0 | Link-Local Address |
ff02::/16 | Begins with ff02 | Scope local multicast |
ff02::1:ff00:0/104 | Pattern: ff02:0:0:0:0:1:ff__:____ | Solicited-Node Multicast Address |
- Range literally includes all addresses that begin fc and fd, but all that begin fc are reserved.
Hex-Binary Conversion Table
Binary | Hex |
0000 | 0 |
0001 | 1 |
0010 | 2 |
0011 | 3 |
0100 | 4 |
0101 | 5 |
0110 | 6 |
0111 | 7 |
1000 | 8 |
1001 | 9 |
1010 | A |
1011 | B |
1100 | C |
1101 | D |
1110 | E |
1111 | F |
Powers of 2
Power | Decimal | Power | Decimal | Power | Decimal |
20 | 1 | 28 | 256 | 216 | 65,536 |
21 | 2 | 29 | 512 | 217 | 131,072 |
22 | 4 | 210 | 1024 | 218 | 262,144 |
23 | 8 | 211 | 2048 | 219 | 524,288 |
24 | 16 | 212 | 4096 | 220 | 1,048,576 |
25 | 32 | 213 | 8192 | 221 | 2,097,152 |
26 | 64 | 214 | 16,384 | 222 | 4,194,304 |
27 | 128 | 215 | 32,768 | 223 | 8,388,608 |
Cisco Annual Internet Report – A page from Cisco with statistics about Internet usage and growth.
2019 Internet Usage Report – A page from Cisco with statistics about Internet usage and growth.
Cisco Document on IPv6 Address Planning – An oldie but a goodie, with details of how to plan for IPv6 addressing and subnets.
Tim Martin IPv6 LiveLesson – Address Planning Video – An oldie but a goodie, with details of how to plan for IPv6 addressing and subnets.
Reserved Multicast Addresses – IANA page w/ reserved multicast addresses used by various protocols, for example, DHCP, NDP, and OSPF.
IPv6 Buzz Podcast – A wonderful podcast about IPv6. Well worth listening to past episodes.
IPv6 Playlist at O’Reilly – Wendell’s playlist of IPv6 titles available at O’Reilly Online.
IPv4 Subnetting Class Notes – A page on this site, used in the IPv4 subnetting course, with links and resources for IPv4 subnetting.
RFC 4632 – CIDR – Defines Classless Interdomain Routing (CIDR), which helped delay the date at which the world consumed all public IPv4 addresses.
RFC 1918 – IPv4 Private Networks – Reserves some IPv4 networks for private use; most often used with NAT/PAT.
RFC 3022 – NAT – Defines Network Address Translation (NAT), which helped delay the date at which the world consumed all public IPv4 addresses.
RFC 4291 – IP Version 6 Addressing Architecture – Defines global unicast addresses (GUA) and others, along with the abbreviation conventions.
RFC 5952 – Address Formats – A short RFC that describes the standard for address abbreviation and other details about how to write and record IPv6 addresses.
RFC 4861 – IPv6 Neighbor Discovery – Defines neighbor discovery protocol, which among other things replaces IPv4 ARP.
RFC 6177 – IPv6 Address Assignment to End Sites – A short RFC that explains the standards for assigning a global routing prefix (GRP) to a site.
RFC 4862 – Stateless Address Auto Configuration (SLAAC) – Defines a process by which a host can form its own IPv6 address based on a prefix learned from a router.
RFC 4941 – Privacy Extensions – Defines an alternative method for SLAAC to create the interface ID (IID), making the IID random, rather than a predictable IID based on its MAC address.
RFC 7721 – Security Issues with Stable Addresses – Explains the security issues that arise when using stable and predictable IPv6 addresses, and summarizes the options available (like RFC 4941 Privacy Extensions.)
RFC 8064 – Recommendations for Stable IPv6 Addresses – A short RFC that defines the suggested RFCs that should be used to dynamically create IPv6 unicast addresses. The RFC refers to methods that do not use MAC addresses and EUI-64, but rather RFCs like RFC 7217.
RFC 7217 – Semantically Opaque Stable IPv6 Addresses with SLAAC – A method to automatically create a host’s IPv6 address with SLAAC that does not use the device MAC address, while making the address stable so that it does not change as long as the host does not move to another subnet.
RFC 8415 – DHCP for IPv6 – A short RFC that explains the standards for assigning a global routing prefix (GRP) to a site.
RFC 8106 – Router Advertisement Options for DNS (RDNSS) – A short RFC that describes how a router can supply the list of DNS server addresses via the NDP RA message.
RFC 6555 – Happy Eyeballs: Success with IPv6 Hosts – A short RFC that that describes conventions to first try IPv6 and then try IPv4, to favor IPv6, while not taking too much time before moving on to try IPv4.
RFC 8305 – Happy Eyeballs V2: Better Connectivity Using Concurrency – A revised definition for Happy Eyeballs (RFC 6555.)
And, some related RFCs that the course does not mention:
RFC 6177 – IPv6 Address Assignment to End Sites – A short RFC that explains the standards for assigning a global routing prefix (GRP) to a site.
IPv4 Address Classes
Class | First Octet Values | Purpose |
A | 1 – 126 | Unicast (large networks) |
B | 128 – 191 | Unicast (medium-sized networks) |
C | 192 – 223 | Unicast (small networks) |
D | 224 – 239 | Multicast |
E | 240 – 255 | Reserved (formerly experimental) |
- First Octet of 0 or 127: Reserved for Special Uses
Powers of 2
Power | Decimal | Power | Decimal | Power | Decimal |
20 | 1 | 28 | 256 | 216 | 65,536 |
21 | 2 | 29 | 512 | 217 | 131,072 |
22 | 4 | 210 | 1024 | 218 | 262,144 |
23 | 8 | 211 | 2048 | 219 | 524,288 |
24 | 16 | 212 | 4096 | 220 | 1,048,576 |
25 | 32 | 213 | 8192 | 221 | 2,097,152 |
26 | 64 | 214 | 16,384 | 222 | 4,194,304 |
27 | 128 | 215 | 32,768 | 223 | 8,388,608 |
Private IPv4 Networks
Class of Networks | Private IP Networks | Number of Networks |
A | 10.0.0.0 | 1 |
B | 172.16.0.0 through 171.31.0.0 | 16 |
C | 192.168.0.0 through 192.168.255.0 | 256 |
The Nine DDN Octet Values
Decimal Value | Binary | Number of Binary 1’s |
0 | 00000000 | 0 |
128 | 10000000 | 1 |
192 | 11000000 | 2 |
224 | 11100000 | 3 |
240 | 11110000 | 4 |
248 | 11111000 | 5 |
252 | 11111100 | 6 |
254 | 11111110 | 7 |
255 | 11111111 | 8 |
Speed Goals and Learning Stages
Subnetting Processes | Book Speed Goals | Your Speed Goal | Your Current Speed | Your Current Stage |
Find Classful Network Facts * | 10 | |||
Convert Mask Formats * | 10 | |||
Find Subnet Facts | 30 | |||
Interpret Design w/ Mask | 15 | |||
Choose One Mask | 15 | |||
Find All Subnet IDs * | 45 |
- Excludes the time required to write all the answers on paper.
Binary-to-Decimal Conversion Chart: Decimal 0 – 127
Decimal | Binary | Decimal | Binary | Decimal | Binary | Decimal | Binary |
0 | 00000000 | 32 | 00100000 | 64 | 01000000 | 96 | 01100000 |
1 | 00000001 | 33 | 00100001 | 65 | 01000001 | 97 | 01100001 |
2 | 00000010 | 34 | 00100010 | 66 | 01000010 | 98 | 01100010 |
3 | 00000011 | 35 | 00100011 | 67 | 01000011 | 99 | 01100011 |
4 | 00000100 | 36 | 00100100 | 68 | 01000100 | 100 | 01100100 |
5 | 00000101 | 37 | 00100101 | 69 | 01000101 | 101 | 01100101 |
6 | 00000110 | 38 | 00100110 | 70 | 01000110 | 102 | 01100110 |
7 | 00000111 | 39 | 00100111 | 71 | 01000111 | 103 | 01100111 |
8 | 00001000 | 40 | 00101000 | 72 | 01001000 | 104 | 01101000 |
9 | 00001001 | 41 | 00101001 | 73 | 01001001 | 105 | 01101001 |
10 | 00001010 | 42 | 00101010 | 74 | 01001010 | 106 | 01101010 |
11 | 00001011 | 43 | 00101011 | 75 | 01001011 | 107 | 01101011 |
12 | 00001100 | 44 | 00101100 | 76 | 01001100 | 108 | 01101100 |
13 | 00001101 | 45 | 00101101 | 77 | 01001101 | 109 | 01101101 |
14 | 00001110 | 46 | 00101110 | 78 | 01001110 | 110 | 01101110 |
15 | 00001111 | 47 | 00101111 | 79 | 01001111 | 111 | 01101111 |
16 | 00010000 | 48 | 00110000 | 80 | 01010000 | 112 | 01110000 |
17 | 00010001 | 49 | 00110001 | 81 | 01010001 | 113 | 01110001 |
18 | 00010010 | 50 | 00110010 | 82 | 01010010 | 114 | 01110010 |
19 | 00010011 | 51 | 00110011 | 83 | 01010011 | 115 | 01110011 |
20 | 00010100 | 52 | 00110100 | 84 | 01010100 | 116 | 01110100 |
21 | 00010101 | 53 | 00110101 | 85 | 01010101 | 117 | 01110101 |
22 | 00010110 | 54 | 00110110 | 86 | 01010110 | 118 | 01110110 |
23 | 00010111 | 55 | 00110111 | 87 | 01010111 | 119 | 01110111 |
24 | 00011000 | 56 | 00111000 | 88 | 01011000 | 120 | 01111000 |
25 | 00011001 | 57 | 00111001 | 89 | 01011001 | 121 | 01111001 |
26 | 00011010 | 58 | 00111010 | 90 | 01011010 | 122 | 01111010 |
27 | 00011011 | 59 | 00111011 | 91 | 01011011 | 123 | 01111011 |
28 | 00011100 | 60 | 00111100 | 92 | 01011100 | 124 | 01111100 |
29 | 00011101 | 61 | 00111101 | 93 | 01011101 | 125 | 01111101 |
30 | 00011110 | 62 | 00111110 | 94 | 01011110 | 126 | 01111110 |
31 | 00011111 | 63 | 00111111 | 95 | 01011111 | 127 | 01111111 |
Binary-to-Decimal Conversion Chart: Decimal 128 – 255
Decimal | Binary | Decimal | Binary | Decimal | Binary | Decimal | Binary |
128 | 10000000 | 160 | 10100000 | 192 | 11000000 | 224 | 11100000 |
129 | 10000001 | 161 | 10100001 | 193 | 11000001 | 225 | 11100001 |
130 | 10000010 | 162 | 10100010 | 194 | 11000010 | 226 | 11100010 |
131 | 10000011 | 163 | 10100011 | 195 | 11000011 | 227 | 11100011 |
132 | 10000100 | 164 | 10100100 | 196 | 11000100 | 228 | 11100100 |
133 | 10000101 | 165 | 10100101 | 197 | 11000101 | 229 | 11100101 |
134 | 10000110 | 166 | 10100110 | 198 | 11000110 | 230 | 11100110 |
135 | 10000111 | 167 | 10100111 | 199 | 11000111 | 231 | 11100111 |
136 | 10001000 | 168 | 10101000 | 200 | 11001000 | 232 | 11101000 |
137 | 10001001 | 169 | 10101001 | 201 | 11001001 | 233 | 11101001 |
138 | 10001010 | 170 | 10101010 | 202 | 11001010 | 234 | 11101010 |
139 | 10001011 | 171 | 10101011 | 203 | 11001011 | 235 | 11101011 |
140 | 10001100 | 172 | 10101100 | 204 | 11001100 | 236 | 11101100 |
141 | 10001101 | 173 | 10101101 | 205 | 11001101 | 237 | 11101101 |
142 | 10001110 | 174 | 10101110 | 206 | 11001110 | 238 | 11101110 |
143 | 10001111 | 175 | 10101111 | 207 | 11001111 | 239 | 11101111 |
144 | 10010000 | 176 | 10110000 | 208 | 11010000 | 240 | 11110000 |
145 | 10010001 | 177 | 10110001 | 209 | 11010001 | 241 | 11110001 |
146 | 10010010 | 178 | 10110010 | 210 | 11010010 | 242 | 11110010 |
147 | 10010011 | 179 | 10110011 | 211 | 11010011 | 243 | 11110011 |
148 | 10010100 | 180 | 10110100 | 212 | 11010100 | 244 | 11110100 |
149 | 10010101 | 181 | 10110101 | 213 | 11010101 | 245 | 11110101 |
150 | 10010110 | 182 | 10110110 | 214 | 11010110 | 246 | 11110110 |
151 | 10010111 | 183 | 10110111 | 215 | 11010111 | 247 | 11110111 |
152 | 10011000 | 184 | 10111000 | 216 | 11011000 | 248 | 11111000 |
153 | 10011001 | 185 | 10111001 | 217 | 11011001 | 249 | 11111001 |
154 | 10011010 | 186 | 10111010 | 218 | 11011010 | 250 | 11111010 |
155 | 10011011 | 187 | 10111011 | 219 | 11011011 | 251 | 11111011 |
156 | 10011100 | 188 | 10111100 | 220 | 11011100 | 252 | 11111100 |
157 | 10011101 | 189 | 10111101 | 221 | 11011101 | 253 | 11111101 |
158 | 10011110 | 190 | 10111110 | 222 | 11011110 | 254 | 11111110 |
159 | 10011111 | 191 | 10111111 | 223 | 11011111 | 255 | 11111111 |
Cisco Certification Portal: (www.cisco.com/go/certifications)
Cisco Pages on the “New” 2020 Certifications
Cisco CCNA 200-301 Info and Exam Topics Page
Cisco CCNA Routing and Switching Page
Cisco Learning Network (CLN): The Cisco Learning Network (CLN) is the best learning community to use when learning for CCNA.
Cisco Recertification Requirements: As of Feb 24, 2020.
Take Cisco Exams from Home: Details of how to take the exam from home.
CCNA 200-301 Official Cert Guide, Volume 1, on O’Reilly (Safari)
CCNA 200-301 Official Cert Guide, Volume 2, on O’Reilly (Safari)
CCNA 200-301 Official Cert Guide, Volume 1, on CiscoPress.com
CCNA 200-301 Official Cert Guide, Volume 2, on CiscoPress.com
CCNA 200-301 Official Cert Guide Library (Contains Both Volumes) on CiscoPress.com
The CCNA Official Cert Guides come with practice questions. You can use some of those practice questions at Safari (O’Reilly Online), and for others you must purchase the book(s). In particular:
- The Safari offering includes all four CCNA Exam banks found in some of the books.
- The Premium Edition eBook products from Cisco Press, namely the CCNA Vol 2 Premium Edition and the CCNA Library Premium Edition, include those same four CCNA exam banks.
- The CCNA Vol 1 and CCNA Vol 2 books include other exam banks: one with all the questions from the chapter pre-quizzes, one with part review questions, and others that cover only the content in that book but not the other volume.
- The print books include two exam banks, rather than four, for the general question types.
Links:
CCNA Questions from Premium Edition CCNA Library, on O’Reilly (Safari)
CCNA 200-301 Official Cert Guide, Volume 1, on CiscoPress.com
CCNA 200-301 Official Cert Guide, Volume 2, on CiscoPress.com
CCNA 200-301 Official Cert Guide Library (Contains Both Volumes) on CiscoPress.com
Premium Edition of CCNA 200-301 Official Cert Guide, Volume 1, on CiscoPress.com
Premium Edition of CCNA 200-301 Official Cert Guide, Volume 2, on CiscoPress.com
Premium Edition of CCNA 200-301 Official Cert Guide Library (Includes Both Vol 1 and 2), on CiscoPress.com
Wendell’s CCNA Blog: A large variety of content about CCNA Content from over the last eight years.
Config Labs for CCNA 200-301: Short configuration exercises for which you do not even need a simulator – just write your config on paper or type in an editor.
Packet Tracer Labs for the Books’ Examples: The blog has a series of posts about how to use Cisco Packet Tracer to re-create examples from the books. Each post matches a book chapter, with a goal of helping you decide which examples can be reasonably done in PT and which ones are probably too difficult to re-create in PT for various reasons.
Pearson Network Simulator: Think of it as like Packet Tracer, but with hundreds of built-in lab exercises, for usually around $100 US.