For questions about Internet Protocol version 4 (IPv4); as specified in RFC791.
0
votes
1answer
15 views
Subnetting Access Problem
I am learning subnetting, and I am using Packet Tracer to design a network for a building with five storeys. I have used subnetting, with each floor having its own subnet. As a result, it is not ...
0
votes
0answers
10 views
Determine IP Pool or subnet IP [on hold]
OS - Ubuntu 16.04
I was taught in class to do this :
host google.com
copy the output IP then
whois <copiedIP> | grep CIDR
this gave the network ID with the subnet mask and hence gave the IP ...
0
votes
0answers
20 views
port forwarding error [on hold]
I have been developing a basic client server program on java for my college network(uses static ip).
The campus network uses ipv4 family as 10.x.x.x or 172.x.x.x.
Suppose that the server(listening on ...
0
votes
1answer
30 views
Communicating with a server connected to wifi network [on hold]
I am student currently working on a networking project on java for my college. My college's network uses static IP addressing and all computers connected to network use 10.x.x.x or 172.x.x.x family.
...
0
votes
1answer
52 views
Why are there IP collisions in my network? [on hold]
So I have a switch connected to ethernet cable which has a static IP address configured on it for IPv4 / v6. there are 3 IPv4 static addresses on its subnet.
I have 2 Anritsu callboxes connected to ...
0
votes
0answers
17 views
IP address conflict according to Linksys [closed]
Apparently my Arris SB8200 Modem is causing an ip address conflict with my Linksys AC2200 Velop Mesh Router. The web gui address for the SB8200 is 192.168.100.1 and Velop is 192.168.1.1. According to ...
0
votes
0answers
24 views
Can access my app via domain name using every port except for 80 [closed]
Here's a new one for you. I purchased the domain name, registered the name servers, and confirmed DNS has propagated.
Then I start my node app with pm2 on Ubuntu v16.04.5 LTS on a Digital Ocean ...
0
votes
0answers
10 views
Calculate supernet of host and host number based on IP and mask? [duplicate]
So I got the following IP: 192.15.205.7 and the following mask: 255.255.252.0.
Now I know that in order to get the supernet of the host I have to use the AND operator between the IP and the mask.
In ...
3
votes
2answers
68 views
How to find the switch IP address based on MAC address?
On PC, the extra network adapter is configured as static 192.168.2.1.
A switch with DHCP enabled is connected to 192.168.2.1 and if I login using the console (RS232) I see that it has 169.254.x.x ...
0
votes
0answers
21 views
Doubt on subnetting [duplicate]
I am learning basics of networks and I have the following doubts:
Is the following statement true?
Subnet mask of a network = Subnet mask of all hosts in the network.
My instructor gave an example ...
0
votes
1answer
81 views
Why is the IP datagram Total length an issue?
I read this about IPv4 on page 440 of Computer Networks:
The Total length includes everything in the datagram—both header and
data. The maximum length is 65,535 bytes. At present, this upper ...
2
votes
2answers
100 views
What can I infer about a network connection using a cable tester (if anything)
I have a NS-468 cable tester for testing cables. This works fine but if I connect just one end of a RJ45 cable to a network, I only get 4 lights. This seems reasonable as I suppose 4 pins are for ...
0
votes
1answer
36 views
Why does arp request get broadcast even though it knows the ip address of receiver?
Since the arp request wants to know the Mac address of an ip address which belongs to any one device what's the purpose of sending a broadcast Anyway even though we know only that ip address device ...
0
votes
2answers
43 views
Fortigate 60D - WAN Link Traffic Division
Requirement is to divide the WAN zone traffic
Two different LAN IP group's internet traffic should go though 2 different WAN connections in fortigate 60D (Currently its WAN Zone(wan1 and wan2) . How ...
0
votes
1answer
57 views
How to find which port has a static IP
My colleague set up a static IP on a switch, but didn't tell me where and what port, is there a command to run that will find which port has the static IP set up on.
-1
votes
1answer
46 views
Can't connect between an IPV6 network and an added IPV4 router
I have a very simple topology, where 4 routers use IPV6 and RIP, there aren't problems and all devices have connectivity. The issue is if I add another router this time using IPV4 for clients.
I ...
0
votes
3answers
82 views
How did one go from IP to MAC in classful networks?
This is more of a question asked out of curiosity than for practical reasons, but it's bugging me, because it might point to a lack of understanding elsewhere. Back when classful IP addresses were ...
0
votes
1answer
67 views
IPv6 - is the transition still urgent? [closed]
Less than a decade ago there was a lot of talk about the urgency to get to IPv6 as the available routable IPv4 space was becoming quickly exhausted. Network World
Even with IPv4 essentially being ...
55
votes
7answers
14k 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,...
0
votes
1answer
32 views
How Pppoe subscriber with static ip sends ipcp request
How a pppoe subscriber with static ip sends ipcp configure request. For dhcp the subscriber can include 0.0.0.0 in configure request of ipcp packet and obtain its ip from remote server. But in static ...
0
votes
5answers
78 views
Trace the IP address
I have created a web application using Django. While running someone entered the admin login and deleted the users. when checked in the access log of Nginx we found the IP address that actually did ...
4
votes
6answers
483 views
Why is classful addressing considered waste?
I am trying to understand the addressing strategies. But there is something which I can't grasp. Maybe I am missing a very basic point, if so, I am sorry beforehand.
From my researches, let's say, if ...
1
vote
1answer
42 views
How much CPU power does it take to process a packet? [closed]
Had a debate with a friend on CPU requirements for networking. I'm not a network engineer, but my understanding is that minimal CPU processing happens for IPv4 network traffic and that it's mostly ...
0
votes
1answer
76 views
Can I force a higher TCP segment size with netcat?
I'm using netcat to send random data from A to B, both Linux machines on Ethernet networks, with a router in the middle. For pedagogic purposes I'd like to force IP fragmentation on the router (Cisco ...
0
votes
0answers
3 views
Is it commonplace / accepted to change an existing CIDR prefix to meet certain network requirements? [duplicate]
Say for example, you have an IP address with a CIDR prefix of /27 (mask of 255.255.255.224) and are required to create 4 subnets each with an equal amount of usable host addresses, would it be ...
1
vote
3answers
317 views
difference between ip checksum and tcp checksum
If an error on a packet occurs on a router, who does detect the error, IP checksum or TCP checksum?
I have understood that the ipv4 checksum detects errors only inside the ip header and the tcp ...
0
votes
1answer
76 views
What is AWS ELB IP range for white listing in firewall? [closed]
I have AWS infrastructure running over AWS ELB (Classic Load Balancer) and EC2.
I need to know IP range for AWS ELB in EU (Ireland) Knexusplatform-Live-SaaS-IR-1436765642.eu-west-1.elb.amazonaws.com, ...
0
votes
1answer
78 views
How to assign 2000 addresses starting from 198.16.16.0? [duplicate]
This problem comes from Tannanebaum's CN book and the full description of it is as follows:
A large number of consecutive IP addresses are available starting at 198.16.0.0. Suppose that four ...
-1
votes
0answers
15 views
How many IP addresses needed for a single wan link? [duplicate]
02.192.168.20.0/24 main network need to be separated into subnetworks based on the following requirements.(VLMS concept)
a. 4 subnets with 25 devices each.
b. 4 WAN links to inter-connect the sub ...
0
votes
1answer
32 views
Understanding IPV4 private address subnetting
I think I have a decent understanding of subnetting however I'm confused with one little portion pertaining to the private address range 172.16/12
I see a lot of places say that this private address ...
0
votes
1answer
42 views
Are there any constraints to Subnetworks? [duplicate]
Using this network mask 255.255.255.0, I can steal 2 bits from the host bits to make 4 subnets.
Now I've never seen it but is it also possible to use the NWMask 255.255.0.0 and also create 4 ...
1
vote
2answers
87 views
How does WAN work?
I understand the basics.
WAN is a network that connects multiple LANs together. Usually the router is the connection between the LAN and WAN. But I have some questions books and the internet could not ...
0
votes
0answers
15 views
IP4 Classes question [duplicate]
Quick Question:
(New to networking) Taking an online CCNA prep course. I am going through a section on IPv4 classes, and can't understand why as you progress through the classes that the network ...
4
votes
1answer
113 views
Internet Protocol version 4 (IPv4) padding?
Where is ip padding insert in ip data-gram format,
after payload?
3
votes
3answers
65 views
How does any program identify the protocol header next from TCP?
I need to know how does wireshark or any other program knows the protocol next from TCP. I mean, for instance:
The Ethernet layer has a field named Type which carry the IPv04
The Internet protocol ...
1
vote
3answers
91 views
Why can't a host B act as a server, and accept TCP connections, when sitting behind a NAT?
Originally, I thought I intuitively understood why B can't accept TCP connections, however when I read about how P2P applications circumvent this exact problem by using an intermediate peer that is ...
17
votes
1answer
3k views
What is the practical use of a /31 CIDR or 255.255.255.254?
With a /31 subnet, we are left with zero usable hosts. The /31 subnet only has two hosts - one for network and another for broadcast.
I am wondering why would someone ever use this subnet.
2
votes
1answer
363 views
Can a 172.168.10.0/28 be a class B Subnet
I am starting my studies in networking and starting off with the basics of IP addressing and Subnetting with CIDR values.
My Question here is 1st how can you tell the subnet class of an IP address ...
0
votes
1answer
49 views
How ARIN IP Address is used in APNIC Region? [closed]
Amazon AWS provides the following JSON (Source) which has list of IP Address ranges used by AWS.
{
"ip_prefix": "54.179.0.0/16",
"region": "ap-southeast-1",
"service": "EC2"
...
0
votes
1answer
86 views
What are the component names of CIDR Prefix Notation?
What are the components of the IETF's CIDR Prefix Notation called?
172.16.0.0/16 contains two parts:
172.16.0.0
/16
In the RFC the entire term 172.16.0.0/16 is defined as the "Prefix Notation" for ...
2
votes
2answers
82 views
Bad mask for Cisco simulator GNS3
I am using the GNS3 simulator, and I need to connect two Cisco C7200 routers.
When I enter the ip address 126.0.0.4 255.255.255.252 command, I get Bad mask /30 for address 126.0.0.4.
1
vote
1answer
162 views
Why did Netflix choose to use CIDR blocks of 100.64.0.0/10 as its private network IP space?
Netflix gave a public tech-talk explaining their network, and one specific design puzzled me. See Page 25 at this talk (Netflix's Migration into VPC), they seemed to choose to use 100.64.0.0/10 as ...
3
votes
3answers
131 views
How to tell which one is the source IP and MAC address of the data being received?
I have to work with an FPGA module already running a code written by someone else. I have no access to the FPGA code.
Now the setup is something like this:-
FPGA is connected to the pc via ethernet ...
1
vote
1answer
76 views
What format is "1.34.128.0/113'?
I know of two format that use similar notation, Classless Inter Domain Routing (CIDR) and Variable Length Subnet Mask (VLSM). However the numbers after the / is usually less than 32. However in this ...
-6
votes
4answers
767 views
What is the difference between DHCP and NAT?
Both seem the same to me. I don't see how DHCP is different from Dynamic NAT. Can anyone please help?
2
votes
2answers
73 views
How does/did an ISP serve so many people over IPv4
Whilst reading Tanenbaum - Computer Networks they talk about IP scarcity at the level of ISPs:
IP addresses are scarce. An ISP might have a /16 address, giving it 65,534 usable host numbers. If it ...
2
votes
2answers
58 views
Before the invention of Classless Inter-Domain Routing (CIDR) did hosts have subnet masks assigned?
Before the invention of CIDR, did hosts also have a subnet mask assigned or only have an IP address and the network was determined by the class of the IP address?
1
vote
1answer
128 views
GNS3 IP helper in Multiple Vlans
Good day everyone, I'am having trouble getting VPCs from VLAN 3 to communicate with the DHCP on Vlan 3 I've also tried configured IP helper on the Router but to no avail.
Router Configuration dump
...
0
votes
1answer
31 views
Netgear GS724T static IP assignment
I have a Netgear GS724T smart switch. I'm not sure if this can be done, but I want to assign a static IP address to each of the 24 ports on the switch so that any device connected to a particular port ...
6
votes
3answers
772 views
Why couldn't a nework address be used as as broadcast address as well?
I am taking a refresher on Networking and I found out that:
Network address is an IP address with all 0s after the subnet mask
Broadcast address is an IP address with all 1s after the subnet mask
...
