Frequent Questions
882 questions
137
votes
6
answers
882k
views
How do you calculate the prefix, network, subnet, and host numbers?
Example:
IP: 128.42.5.4
In binary: 10000000 00101010 00000101 00000100
Subnet: 255.255.248.0
How could you determine the prefix, network, subnet, and host numbers?
- 1,459
43
votes
7
answers
18k
views
OSI Model and Networking Protocols Relationship
When most networking students first learn about the OSI model, they spend a great deal of time trying to figure out which layer of the model a particular protocol fits into. We get a lot of questions ...
- 68.3k
11
votes
4
answers
26k
views
The maximum length of CAT6 for intranet network?
Recently I purchased CAT6 cable with a length of 150 meter. I bought another CAT6 with a length of 148 meter. I joined both the cables using RJ45 cable coupler. I tested it using LAN TESTER, and ...
- 213
76
votes
5
answers
23k
views
Why are IPv4 addresses running out?
I understand that we are running out (or ran out already?) of IPv4 addresses, but I don't really understand why that is. Right now, every home has its own IPv4 address (dynamically assigned, but still,...
- 871
30
votes
4
answers
76k
views
How does a switch learn a switch table?
Say the switch table is empty. If computer A sends a frame destined to computer B, the switch will broadcast asking who has the MAC address of B. What if C suddenly sends a frame to A? What is the ...
- 835
188
votes
9
answers
119k
views
Why do we need a 3-way handshake? Why not just 2-way?
The TCP 3-way handshake works like this:
Client ------SYN-----> Server
Client <---ACK/SYN---- Server
Client ------ACK-----> Server
Why not just this?
Client ------SYN-----> Server
Client ...
- 1,993
88
votes
4
answers
429k
views
Why and how are Ethernet Vlans tagged?
I hear about VLAN tagging, but I don’t quite understand the concept. I know a trunk cannot accept untagged packets without configuring a native VLAN, and that access ports only accept untagged ...
- 1,099
7
votes
2
answers
3k
views
NAT Overlapping
I am trying to do some networking lab. Basically, I have a network like this:
So, is it possible to configure NAT router in such way, that PC1 and PC2 can access remote HOST and each other. The ...
- 173
265
votes
6
answers
506k
views
11
votes
2
answers
17k
views
In IPsec VPN, how is the pre-shared key encrypted?
I was doing IPsec VPN on ASA 8.0, and I understand a little about that. The initiator starts by sending its ISAKMP policy to the responder, and the responder sends back the matched policy. After that, ...
- 153
19
votes
6
answers
11k
views
Why use IP if we already have a MAC address?
I am preparing for ICND1 exams and recently started to learn about different Cisco devices.
I have just come to know how the packet is generated to be transmitted over a network, or outside the ...
- 459
5
votes
1
answer
1k
views
How do ARP requests work
So I may have a stupid question that mainly comes from me getting weird results to say the least while experimenting.
I'm a bit unsure how do ARP requests work.
For example how can I arp my entire ...
- 153
11
votes
6
answers
29k
views
Can a single optical fiber support full-duplex communication?
Can a single-mode single optical fiber support full-duplex communication, or does it have to be two fibers, one for each direction?
- 233
9
votes
3
answers
8k
views
Implementing Cisco QoS model to end users
I have implemented the 4-Class QoS Model as described in this earlier post from 2013. This Core configuration is implemented on a Cisco VSS 6509-E setup running software version: Cisco IOS Software, ...
user36472
5
votes
1
answer
1k
views
Finding Subnet Ranges of IPv6
I need to find a single subnet range to cover 10,000 IP addresses (hosts), given the IPv6 Address 2405:1300:c5c1:322::/108 (for example)
I am aware of how to do subnet in IPv4 but cannot grasp the ...
- 153