Questions tagged [ipv4]

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

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RESEDENTIAL IP OR DATACENTER IP, how to only allow only real humans (without using reCAPTCHA or any such)? [closed]

how do i figure out if a HTTP request to my website is by a real user? in other words, what are factors that determine if IP is a residential IP or data-center/hosting/commercial IP? is only geo-...
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IPv6 Hardware and Software [closed]

what are the impact of the introduction and use of IPv6 on hardware and software, mainly focusing on switches and routers?
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Why do I still get public IPv4 address whenever I move even though we’re running out of them? [closed]

I have done some google search and could not find any good explanation. I have the background of networking, but isn’t Comcast running out of IPv4 addresses? If so, that means I must have shared my ...
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Why does the IPv4 datagram header contain a `Total length` field instead of having a `Data length` field? [closed]

Based on RFC 791 and Data Communications and Networking, V Edition, I can say that Total length helps in fragmentation process. And because of that, the value of MTU also focuses upon Total length. We ...
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2answers
30 views

why ip protocol use fragment offset instead of index number?

I was wondering why the IP protocol use fragment offset to define the fragments of an IP datagram instead of using index number (first fragment with index 0, second with index 1, ...). We already know ...
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2answers
43 views

Can a host from different subnet bypass the network mask validation of destination host and communicate on layer 2?

I am aware that a host will always check the subnet of the destination node before the transmission in order known if it has to send it to the gatewey for different subnet. However, would it be ...
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1answer
23 views

Understanding IP scheme, distribution and usage [duplicate]

I'm new to networking and I'm doing my best to understand how things work. I do have a problem in understanding IP scheme idea (even though obsolete), more specifically, their structure, distribution ...
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9 views

How to calculate the prefix of an IP Address? [duplicate]

I know there are many questions/answers for this already but i'm really confused on how the prefix of an IP is calculated. I'm currently doing an mock paper for an exam and the question goes like this:...
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1answer
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How can I assign a static public ip to a machine behind a router?

I know about port-forwarding, but I'm interested in how to make a machine on a local network available to the public internet without port-forwarding.
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1answer
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Default subnet question [duplicate]

Very new to network engineering. I just watched a really good series of videos on YouTube explaining IP addresses, subnet masks and the class system for IPv4. There was one bit which got me confused ...
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3answers
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Will IPv6 make private IP addresses become obsolete?

Will it still be useful to make use of private IP addresses with IPv6?
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1answer
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I don't understand IP addressing for a router

I am taking an internet (CISCO) course and don't understand the difference between the default gateway address for a router and its IP address. In every example of the class the default gateway ...
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Determine the range of IP's avaliable for hosts on a subnet /28 [duplicate]

I am looking into my Virtual Switch configuration( Hyper-V ) and i am confused how the range of valid IP's is determined. The IP for configured for the "Virtual Switch" adapter is: IP: 192.168.53.65 ...
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2answers
205 views

transferring IPv4 /32 to another datacenter

We are planning to migrate one set of IPv4 /32 series owned by us, from one dedicated server provider to another provider. Is it necessary to have permission to release the IP series from previous ...
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If a server has both IPv4 and IPv6 addresses, how does the DNS determine which to return? See the following example [closed]

These Pings were done at different times of the same day: C:\Users\LPress>ping www.ucla.edu Pinging gateway.lb.it.ucla.edu [164.67.228.152] with 32 bytes of data: C:\Users\LPress>ping www.ucla.edu ...
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Layering unicast addressing over multicasts

My question has to do with layering of unicast over multicast and has two parts. Part 1. IP unicast over MAC multicast First part of the question is whether there is a standard that prohibits use of ...
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1answer
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Able to ping Domain internal address on home network, why? [closed]

I have a strange issue, I am able to ping my company's internal address (ex: hq.mycomapny.com) when I am on my Home network (WI-FI or Enthernet) and NOT connected to the VPN. When I do a ping on the ...
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Are network IP addresses ever used as source or destination IPs? [duplicate]

The first IP address of an IP subnet is the network address, which stands for the whole network, while the last address is the broadcast address. As far as I understand, we never really send packets ...
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1answer
46 views

IPv4 maximum datagram size

The IPv4 datagram consists of two parts:the header length and the payload. The maximum header size is 60 bytes and minimum is 20 bytes. The maximum size of the data can be 65515 bytes. So why the ...
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1answer
144 views

Broadcasting to unknown Class C Network

I am trying to use python to broadcast to my local network, and I cannot find a way to get the subnet mask. I have been suggested to use the default Class C network subnet mask 255.255.255.0, and use ...
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2answers
45 views

Where are broadcast packages filtered out

When I have one network with a switch. Within that network I have 10 PC. Halve of them are configured within the 192.168.1.0/24 range and the other halve is configured at 192.168.2.0/24. This means I ...
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1answer
38 views

Find Routes not containing these subnets [closed]

Let's say I have 1000 ranges and I would like to make routes that doesn't match these ranges, anyone has any particular tips or tools to share beside doing math ? Example : I have these ranges 13....
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1answer
63 views

Why Classful addressing is not in use if we can subnet them?

So, Let's think that organization needs 5000 IP addresses. Giving 20 C Class IP addresses will cause of adding 20 entries for ISP router. That's problem. We could give Class B IP address, but that ...
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How to find minimum of hosts bits needed and assign equally to five subnets? [duplicate]

I have a 192.168.1.0/18 network block. How do I determine the minimum number of host bits to be borrowed and assigned equally to five subnets? How to calculate the number of users that can be ...
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2answers
53 views

The MSB of IPv4 flags

In IPv4 header, there is 3 bits field called "flags". The MSB of this field must be reset to zero (as many networking blogs say without telling why). i want to know what will happen if I managed to ...
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2answers
57 views

Do NAT devices need to have private IP addresses?

If a NAT's job is to create mappings between internal ip/port pairs and external ip/port pairs with one Internet-routable IP address, does a NAT need a private IP address for itself? I think one ...
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2answers
141 views

Routing Table Settings To Access An Internal Network Through VPN

I have a remote computer behind a VPN (which I have no control of). The IT team of the remote factory wanted me to install Palo Alto Networks' Global Protect program to access the VPN, which is ...
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1answer
70 views

Can I run 2 separate ranges on the same physical network

My current set up is 1 router and 2 switches, the router being 192.168.10.1 with a connection to each switch then 8 and 10 devices on the 2 switches all 192.168.10.x I have an NVR with 2 ports, 1 of ...
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2answers
60 views

When a packet is received, how does it know which internal machine to send it to?

I am familiar with ARP and routing, but I think I am failing to put two and two together here. On an IPv4 packet we have the source IP address, which allows any router to send the response back to the ...
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1answer
42 views

Is an IP broadcast always a layer 2 broadcast also

On my PC I see 255.255.255.255 in ARP with MAC FF:FF:FF:FF:FF:FF, so I'm assuming that in most cases the L3 broadcast is also encapsulated into an L2 broadcast frame, but is this standardized? For a ...
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2answers
58 views

Why can some people use public ip address to access a server from an internal network with the client device within the internal network

As the title suggests. I find it mind breaking to think how network architecture can differ to allow/not allow using public IP address to access a server within internal network from within the ...
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How can I configure a Cisco router 4300 to allow internal server ip:80 to be accessed on public ip:4500

I have an internal web server on port 80. I need help commands maybe to configure port forwarding to access the server on my private network from a public IP Current running config interface ...
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2answers
404 views

MTU the most Confusing Networking term. Lot of questions

I have ton of questions and i feel this is most confusing term for me. The more i read the confusion deepens. I am not able to connect dots. please help. Do we need MTU adjustment with EoMPLS/dot1q ...
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1answer
40 views

IPv4 Subnetting for 1200 or more devices for WiFi

I am currently looking over my schools existing Subnets and their usage. Some seem to be sufficent, others not so much. What is the best practice when you need to support 1200 or more devices on a ...
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2answers
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Question about the destination IP inside an IPv4 packet

I'm reading about link and network layers for the first time and I'm trying to put the pieces together to understand how they work together. My question may not have to do with the link layer but I'm ...
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Given a subnet mask, how can I determine which addresses can be assigned to public network hosts? [duplicate]

For example, I'm given a subnet mask of 255.255.255.248 and need to determine from a list - 16.70.118.63 134.178.18.56 200.47.224.159 68.111.178.93 192.168.16.87 217.37.10.192 - which addresses can be ...
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Building simple network configuration [duplicate]

For the below network configuration I need to propose an IP addresses, netmask and anything else obvious that I am possibly forgetting. The network is built of four Computers, Router and a Switch. I ...
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5answers
9k views

Usage of 192.168.xxx, 172.xxx and 10.xxx in private networks

I know that the organization that distributes IP addresses decided to assign 192.168.xxx, 172.xxx and 10.xxx to private networks. However, I thought that private networks have their own address space ...
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Is it possible to access 127.0.0.xxx in anyway [closed]

So I've been configuring my network at work. We've got a lot of devices from NAS servers to Dante AoIP devices. While configuring some of my devices I managed to set the IP adress of one device to ...
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3answers
2k views

Does NAT violate end to end argument?

Does NAT violate end to end argument? What does end to end argument means in this context?
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56 views

How is it possible to have a default gateway outside of the network range of any interface? [closed]

I always thought that the default gateways has to be on the same network as the server/client trying to connect to the internet. However today I rented a server from Hetzner and the server is able to ...
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2answers
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How TCP connections between origin and node servers over a BGP Anycast gets established?

Server A and B have the same IP address with anycast. Server B connects to the origin server that is very close to server A and very far away from server B, since server A is closer, the response will ...
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1answer
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Remotely Connecting an IPv6 Computer to a IPv6 Private Web Server

I have a private web server at my office, and I want to access that server remotely at my house via IPv6. My office has both IPv4 and IPv6 enabled, but my home has only IPv6. IPv4 works, but I have ...
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2answers
111 views

Loopback with / 32

When we dealing with bgp, osp. Why do we especially use loopback interfaces with / 32!? Is there an advantage or something different from other subnets like 24.
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Why is the source / destination address ordering in IPv4 and IPv6 headers opposite of Ethernet source and destination MAC addresses? [duplicate]

Engineers always do things for a reason. I've noticed that in Ethernet frames, the ordering is destination MAC address first, and then the source MAC address. What's the reason for reversing the ...
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1answer
43 views

Setting the network address freely [duplicate]

I'm trying to understand IP Addressing, but there's something what's still not clear for me. With mask 1111111.1111111.1111111.00000000 (/24) Am I able to set network address "freely" like this? ...
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1answer
49 views

Next Header field in IPv6 vs Protocol field in IPv4, any difference?

So I am new to the IPv6 concept, and I seen that the Protocol field seems to be replaced with Next Header, and I have a question. Question: Is Next Header a complete replace of Protocol, or is they ...
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3answers
120 views

What is the intuition behind subnetting a base IP?

Take a look at this picture: My professor usually gives a topology like this and gives me a base IP. Let's say the base IP given is: 223.1.0.0/24. We're then asked to construct the given topology by ...
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1answer
87 views

Confusion about IANA “Protocol Numbers” registery

In the IANA registery for "Protocol Numbers", there listed 2 IP protocol versions: IPv4 at #4 and IPv6 at #41. Their "protocol" column says IPv[46] Encapsulation, and "reference" column points to 2 ...
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3answers
216 views

Will pinging the multicast “all hosts” IP 224.0.0.1 fill my ARP cache with all hosts on my current subnet?

Just wondering in case I ever have a want / need to see all the hosts on my subnet.

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