Network+ Flashcards
Number of subnets
2^zeros borrowed from classful (from the left).
Number of hosts per subnet
2^(host bits - 2). Host bits are zeros from the right side.
802.11a
“a” for the beginning. It uses 5 GHz frequency, which has shorter range (in my head that equates to weaker) than 2.4 GHz. Just remember 5 GHz and 5 for 54 Mbps.
802.11b
B for better range. It uses 2.4 GHz frequency, which has longer range but lower speed. Just remember 2.4 GHz and 2.4 has 2 numbers, and so does 11 Mbps.
802.11g
G, better than “b”, which rhymes with g. It uses the same 2.4 GHz as “b” and it has 54 Mbps. Since you’re upgrading from b, whose flaw was its throughput, remember that “a” was 54 Mbps too, and that will help you remember that “g” is also 54 Mbps.
802.11n
It uses both frequencies (2.4 GHz and 5 GHz). The way I remember this is (a n g) (as in “n” = “and”). 802.11n has much higher speed (600 Mbps). Just remember N as negative, which could also be said as 2 subtract 8 (the 8 from 802.11 and the 2) to get 6. (6 reminds you of the throughput of 600 Mbps). It also introduces MIMO, which is easy to remember because M comes before N.
802.11ac
The way I remember this, I remember 802.11a frequency is 5 GHz, then you can remember AC is also 5 GHz (a being what ties them together). However, AC uses MU MIMO. Just remember AC is the first 802.11 standard with multiple letters (AC), which will then remind you of multi (i.e. MU(user) MIMO). The 8 in 802 will remind you that there are 8 channels (the multi should trigger your memory for the 8). Each channel will support a throughput of 867 (notice the 8), which comes out to roughly a total of 7 GB.
802.11ax
Last but not least, probably the easiest one to remember, 802.11ax. I basically just remember that this is the most recent one, so it’s going to bring them all together. If you need help remembering, an “X” looks like two arrows pointing towards each other (i.e. bringing them together), which reminds you that 802.11ax can do both frequencies. You’re also using multi-MIMO. I usually just remember X as 10, because your max throughput with all channels is 10 GB (9.6).
Copper cable and Fiber ethernet standard
Memorize.
IP Classes
IP addresses belonging to class A ranges from 0.0.0.0 – 127.255.255.255.
IP addresses belonging to class B ranges from 128.0.0.0 – 191.255.255.255.
IP addresses belonging to class C range from 192.0.0.0 – 223.255.255.255.
Class D does not possess any subnet mask. IP addresses belonging to class D range from 224.0.0.0 – 239.255.255.255.
IP addresses belonging to class E are reserved for experimental and research purposes. IP addresses of class E range from 240.0.0.0 – 255.255.255.255. This class doesn’t have any subnet mask. The higher-order bits of the first octet of class E are always set to 1111.
Special range IP addresses
169.254.0.0 – 169.254.0.16 : Link-local addresses.
127.0.0.0 – 127.255.255.255 : Loop-back addresses.
0.0.0.0 – 0.0.0.8: used to communicate within the current network.
Private IP Class
The range for Class A IP addresses is 10.0.0.0 to 10.255.255.255. This class is used for large networks and is commonly used in large organizations and enterprises.
The range for Class B IP addresses is 172.16.0.0 to 172.31.255.255. This class is used for medium networks and is often used in schools, universities, and businesses.
The range for Class C IP addresses is 192.168.0.0 to 192.168.255.255. This class is used for smaller networks and is commonly used in small office or home networks (SOHO networks).
ping
Testing reachability using ICMP.
ipconfig/ifconfig/ip
Determine computer/s network configuration (TCP/IP).
ipconfig: Windows
ifconfig: Linux
ip: Linux
The ip command has more features and a broader scope than ifconfig. For example, ip can add or remove IP addresses, configure routes, and manage ARP tables. Ifconfig is limited to basic configuration tasks.
nslookup/dig
Look up information from DNS servers.
nslookup: quick one-line DNS resolution results.
dig: more thorough DNS results with better formatting and readability
