Questions tagged [ipv4]

For questions about Internet Protocol version 4 (IPv4); as specified in RFC791.

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390 views

Dividing IPv4 Network into 7 Subnets? [duplicate]

I've been trying to figure out how to divide a network IPv4 IP Address into 7 subnets, where each subnet requires a different number of hosts. For example I have the question: "You are an intern at ...
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1answer
71 views

How can hosting providers give you a dedicated IP adresses?

Some hosting providers give you an option to get a dedicated IP address with your hosting package. For example: Digital Ocean gives every droplet that you create its own dedicated IPv4 address. I can ...
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1answer
649 views

How does a packet travel across multiple routers/subnets?

After reading various resources and examining the example below, the step-by-step process for a packet to travel the route below is still not 100% clear to me. I'm hoping to get clarification. Image ...
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1answer
147 views

Basic IPv4 Question

I just recently learned about IPv4 and the different classes. Let's say I have a following arbritary IP address : 12.123.123.45 Now, the first octet is below 127 and thus, it tells me that this IPv4 ...
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2answers
355 views

What Cisco will discard TTL=1 packets for own interface?

There have been a number of questions about router behaviour with IPv4 packets with TTL=1 and apparently contradictory answers. This question is not about what should a host or router do, it is a ...
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2answers
5k views

(CISCO Packet Tracer) Overlap Error

I am trying to set up a network of for different organisational departments based on a given typology: Using Cisco 2911 routers & 2960-24TT Switches. With given addressing of: 'EIGRP 101' 172....
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1answer
67 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 ...
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1answer
96 views

Communicating with a server connected to wifi network [closed]

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. ...
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1answer
88 views

Why are there IP collisions in my network? [closed]

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 ...
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2answers
972 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 ...
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1answer
126 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 ...
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1answer
97 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 ...
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2answers
522 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 ...
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1answer
67 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.
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1answer
147 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 ...
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3answers
92 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 ...
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1answer
91 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 ...
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7answers
18k 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,...
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1answer
165 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 ...
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5answers
106 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 ...
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6answers
2k 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 ...
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1answer
90 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 ...
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1answer
1k 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 ...
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3answers
8k 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 ...
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1answer
2k 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, ...
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1answer
2k 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 ...
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1answer
82 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 ...
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1answer
94 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 ...
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2answers
215 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 ...
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1answer
807 views

Internet Protocol version 4 (IPv4) padding?

Where is ip padding insert in ip data-gram format, after payload?
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3answers
97 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 ...
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3answers
417 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 ...
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1answer
5k 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.
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1answer
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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 ...
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1answer
203 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" ...
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1answer
453 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 ...
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2answers
414 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.
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2answers
2k 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 ...
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3answers
380 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 ...
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1answer
92 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 ...
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4answers
13k 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?
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2answers
245 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 ...
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2answers
142 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?
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1answer
464 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 ...
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1answer
171 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 ...
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3answers
835 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 ...
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1answer
102 views

IP address that can not be reached from outside of device

I am sorry if this is a silly question, but I am developing an application that should connect to itself over sockets, but to make it secure it should only be reachable from local device. I believe I ...
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1answer
105 views

Sending image files using GNS3

I had built a network using GNS3, this network contains a lot of routers, the problem is: I want to send an image file between these routers using GNS3 is there any way to do that?
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3answers
5k views

When is 'Timestamp' and 'Timestamp Reply' are used in ICMP protocol?

I started the packet capture in my laptop through Wireshark application. Now through cmd, I pinged some server (say, www.google.com). And i stopped packet capture and analysed the packets being ...
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2answers
355 views

TTL used during fragmentation

Hypothetical case Let's say router (R1) receives a IP datagram of length:820 (header + payload) with TTL:255, and ID:11. The outgoing link has an IP-MTU of size 420. Now R1 has to fragment the ...

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