Questions tagged [ipv4]

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

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Accessing a Device on a Separate LAN [closed]

I have the following scenario. There are two users on their own home networks, with their own routers with the following settings. User 1 Public IP of router - 111.111.111.111 Private IP of router (...
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Can I ping someone else's router? [closed]

I want to test if a friend's router is working by pinging it. I have their public ip (ipv4), but no pings seem to be received. Is their router really down, or am I doing something wrong?
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How does RIRs actually ensure IP ranges ownership

I'm currently learning about CIDR, subnets and IPv4 classes. I understood that IPv4 classes were used to route traffic in the beginning but nowadays we use "dynamic" subnet masks with the ...
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How does a device receive default gateway IP address?

When and how does a device get information about default gateway in LAN? I know you can define default gateway statically, but which protocol is used when it is not statically defined? Is it from ...
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Divide IPv4 network into subnets in a SPECIFIC order [duplicate]

My private addresses start at 10.10.0.0/16. I must make 2 subnets with 120 and 450 starting with the 120 one and not leaving any unnecessarily unused addresses. Let me remark, it's IMPERATIVE that the ...
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Are the IPv4 datagram addresses the corresponding public addresses, or the private addresses?

Inside the IPv4 datagram, there are the source and destination IP addresses. The first indicates the IPv4 of the source host, and the second indicates the IPv4 of the destination host. Are these ...
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Why do we need private IP address range?

When it comes to local networks, you have the freedom to use any IP address you want for your network since it doesn't need to communicate on the internet with other devices. However, the RFC ...
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A question from an online subnetting quiz [duplicate]

Does anyone know the last usable host IP address for the 172.45.120.0/23 network? And an explanation of how you got the answer? It's a multiple choice question on an online subnetting quiz. I'm ...
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Why is my assignment asking me use 172.16.0.0 private addressing and IPv4 sub netted Class C address Scheme?

I am doing a project for Cybersecurity and trying to build a college campus network. The complete instructions read: LAN infrastructure layouts for all campuses. • Represent multiple building/...
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Why does one say IP fragmentation is bad and to be avoided when in reality data always needs to be fragmented for MTU compatibility?

Why does one say fragmentation is bad and must be avoided due to performance issues when in reality fragmentation intrinsically occurs within the communication ? Example: User1 wants to send 100 000 ...
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How routers route packets to a specific network

As I understand it, routers route packets to a specific network based on network id and of course the network id must be unique on the Internet, now the question is: maybe there are billions of ...
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rules regarding IPV4 fragments and piecing them together

I'm rolling off my own TCP/IP stack for DOS and I have a question on IPV4 packets. Assuming that a client sends multiple IPV4 fragments, I would predict the MF flag would be set for every fragment ...
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How is the subnet mask detected over the internet with CIDR (classless inter domain routing)?

Lets say there are two public IP addresses. One is 21.120.12.8/16 and the other is 21.120.12.8/8, they are different network IDs but when used over the internet how are they both differentiated? Or is ...
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Extract Palo Alto ACC stats in text format

I have a Palo Alto p220 firewall, which acts as a virtual router at the same time. I would like to get the traffic data (download/upload in bytes per IP) in a format, which I could then parse on my ...
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What is the maximum number of networks in IPv4?

From my understanding, in IPv4 addressing, the first 2 octets identify the network, meaning 2^16 networks can exist. But that doesn't seem even closly enough as the population in even USA is above 300 ...
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Basic conceptual questions about network interfaces

I have some basic questions as I am trying to understand the concept of network interfaces a bit better. Is network interface same as network interface card (NIC)? If not, what's the difference. What ...
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Can a client-side outbound TCP port be reused concurrently for multiple destinations?

Can a client-side outbound TCP port be reused concurrently for multiple destinations? If it's possible, this would let NAT gateways milk an IP Address much more, and make it practically impossible to ...
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ECT Marked ICMP Responses

For ongoing research I'm conducting, I'm measuring the modification of ECT fields of the IPv[46] header. To do this I'm relying on ICMP quotations to inspect what packets 'look like' as they traverse ...
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Into how many subnets can you split this address range up at most? [duplicate]

Let's say there is address range given: 124.33.66.0/23. Into how many subnets can this address range be splitted up at most if each of these subnets includes at least 5 devices? I don't know where to ...
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Why did we not run out of IPv4 adresses yet? [duplicate]

I know how IP addresses work and I also understand the reasons why there is a natural limit to those addresses, as well as the solution to that problem. Officially, we have ran out of IPv4 addresses ...
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What is the use of a host mask/ wildcard with respect to subnetting and ranges? [duplicate]

Taking the example of 10.0.0.0/20, that means my range is 10.0.0.0 to 10.0.15.255 I got that range because I know that the wild card is 0.0.15.255 and I just add it with the beginning address 10.0.0....
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Why does this ip address give me an error “must be valid ipv4 cidr”?

If I set up an AWS VPC with CIDR of 10.0.0.0/20 then the range is 10.0.0.0 to 10.0.15.255 I make a subnet now. Why does 10.0.15.15/28 give an error. Isn't it's range 10.0.15.15 to 10.0.15.30 which is ...
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Why did the IANA specifically choose these ranges for the the private IP address space? [closed]

10.0.0.0/8 IP addresses: 10.0.0.0 – 10.255.255.255 172.16.0.0/12 IP addresses: 172.16.0.0 – 172.31.255.255 192.168.0.0/16 IP addresses: 192.168.0.0 – 192.168.255.255 Is there any reason behind ...
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Routing IPs through another ASN

So currently we have a few /24 ranges that we are looking to use on an upcoming project, we also have an ip circuit with a tier-1 ISP and bgp peering is established. Me and my business partner know ...
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Why DNS services Like google public DNS and Cloudflare 1.1.1.1 has ipv6 versions?

I understand the need for ipv6 as we ran out of ipv4 but dns resolvers like google and cloudflare already have ipv4 addresses for resolving dns and i don't see compatibility as a reason either because ...
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120 views

Ping to default gateway failing

I am trying to ping to a default gateway which i have configured as 171.2.0.1 but somehow the ping is failing . I am new to network domain so i have less idea about it . Any help is appreciated .This ...
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Need a little clarification with NAT and IPv6

I understand NAT exists to not exhaust all the ipv4 addresses so there is no need for it with ipv6. So with ipv6 having an unimaginable amount of addresses, will every device have its own public ...
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Confused in what maximum number of hosts and maximum number of subnets mean [duplicate]

Given a 172.12.0.0 /16 to be subnetted to appropriate networks. Branch 1 has 80 hosts, Branch 2 has 31 hosts and Branch 3 has 75 hosts. I've already made a subnet table based on these using VLSM: ...
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Loopback interfaces subnets [closed]

Assuming that loopback interface is always alone in its network, what are the practical reasons to have IPv4 subnet prefix shorter than /32 for these interfaces? Moreover, why according to various ...
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Routing with private addresses

Let's say that we have a private network, with private addresses and a NAT enabled router at the end. If the router is misconfigured and routes traffic to the global internet, keeping as source ...
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Combining NAT an tunneling

I was reading a text and a doubt came to mind. Suppose there is an interface in a router that implements NAT. That same interface is the extreme of a tunnel. If I was to send a message through said ...
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“SWIP” Equivalent for RIPE?

With ARIN, I was familiar with using "SWIP" for IP blocks via an ORG and a POC. With RIPE, however, it seems that it's different. I have access to a RIPE account where I can make the changes,...
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One client: static IP vs Static lease DHCP vs. DHCP limited range to 1 slot

I want to attach one client (only 1 maximum) to network router ethernet port. I want to always know the client's IP address, for my port forwarding settings. Using DHCP with range the client IP could ...
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Is the routing table used when sending IP packets to a host on the same LAN in ipv4?

I am having trouble understanding the steps in order to send an ip packet to another host on the same LAN. Most sources online that I have read and people I have talked to say that the host uses the ...
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By General Convention if we say the Frame size is 1KB do we take it as a 2^10 Bytes or 10^3 Bytes

In my academic we generally follow 2^10 Byte approach , I m really at loss is it by convention only at my college or something which is accepted widely
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Is not 192.168.88.1 (192.168.*.*) always an “internal” IP address?

I had some headache with a proxy setup which I couldn't figure out. Turns out that only "127.0.0.1" and "localhost" were recognized as "localhost" or "internal" ...
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How to find the first and last address in the FIRST AND LAST SUBNET [duplicate]

So there's a problem that literally stress me out every time I look at it. It's like I almost understand it until I get to knowing how to find the first and last host in the LAST address (last subnet)....
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Are there broadcast/collision domains on non-Ethernet networks?

What if we have routers or hosts connected via ATM, Frame Relay, or SONET; that is, what if we have IP over SONET, IP over ATM, IP over Frame Relay, etc., do we still have broadcast domains and ...
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IPv4 and UDP/TCP packets inside of ICMP packet?

A week ago, after opening wireshark, i was surprised by seing a storm of ICMP packets from different IP addresses. While deep analysing of thoses packets, i noticed that those ICMP packets contains ...
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IPv4 and IPv6 Source Address field

Both the IPv4 and IPv6 headers contain the source address field. What are the reasons for including this field? Is it for to trace which who sent this packet if it get's lost?
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How does the IPv4 Total Header Length field & Fragmentation work together? [duplicate]

I recently learnt that the maximum value of the IPv4 Total Header Length field is 65,535 which equals approx. 65.5KB. To my understanding, it is different from the IHL field as it includes the ...
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Why does sub-netting not give us more addresses? [duplicate]

Sorry if this is dumb, but I am very knew to learning about networks. Here is my reasoning? Let's take the address, 24.50.12.4 if we subnet it with /16 then the network address is 24.50 + host is 0.0....
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How to find Best Fit Mask [duplicate]

How does i find the best fit netmask (i.e., resulting in as few host addresses as possible) for a network with 62 hosts in it? I don't have any class like A,B,C How can i find best fit netmask for ...
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Confusion about TTL when pinging

TTL value of a packet is supposed to decrease 1 at each router from 255 down to zero as follows: But when I ping to 8.8.8.8 the TTL starts at 253 and doesn't change: How can this be explained? Why ...
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Is 12.23.34.45/24 a valid IPv4 subnet definition? [duplicate]

I believe the question says it all: when referring to an IPv4 subnet, is it valid to use 12.23.34.45/24? If it is, is it equivalent to 12.23.34.0/24? If it is not, can you refer me to helpful ...
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Understanding IPV4 address range [duplicate]

I do have basic understanding of IP Address which is unique address for each System either in an organization or over the internet. But i want to understand what is IP address range Lets Say we have ...
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How does the shortage of IPv4 public IPs influence existing firewalls?

I came to know recently IPv4 public IP address pools are going to be exhausted soon. If IPv6 addresses are fully in use, all device vendors like Cisco, Fortinet, Palo Alto have to redesign their ...
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How does IP fragments assembled when identification number field is too small?

Please take reference from this question. It is said in RFC 6864 that if IP V4 IDs remain unique during MDL, it would limit speed to max 6.4Mbps. Now high speed devices generate data at a much higher ...
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1answer
26 views

Connecting to device which requires specific IP [closed]

[Disclaimer: I'm a complete networking novice, and this question might not even be well suited for this site. I welcome pointers to other stack exchanges if appropriate.] I'm trying to connect a ...
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1answer
29 views

What are some techniques to infer the subnet being used? [closed]

Given a list of thousands of IPv4 addresses and that you have no direct access to these hosts, is there a service or a methodology to infer a subnet that's possibly being used?

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