Questions tagged [ipv4]

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

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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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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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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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Understanding L2 Switch (Network Noob)

I currently have the setup on the left and it works just fine... I use it to transfer data between laptop and embedded systems hardware device. (Data...Not internet) Question: What would the set up on ...
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1answer
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TCP protocol mystery [closed]

I am attempting to compile, with pcap-filter, the following string: host yb-in-f91.1e100.n Obtained from the following command: netstat -t output line: tcp 0 0 os-info:portnum yb-in-f91.1e100.n ...
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Is the outgoing interface of a router in the same Subnet as the Incoming interface of the NEXT HOP router?

In the TCP/IP Volume 1, it is stated that ARP works only on the same subnet. Does this mean that the outgoing interface of a router is necessarily on the same subnet as the incoming interface of the ...
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What is the need for the NEXT HOP coloumn in the routing table when we already mention the OUTGOING INTERFACE in another coloumn?

If the OUTGOING INTERFACE is already mentioned in the routing table, it is natural that the next hop will necessarily be the router attached to the outgoing interface. Then why is there a separate ...
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different network mask and subnet mask and netmask [duplicate]

1- what is network mask? 2- what is subnet mask? is there any differnt between network mask and subnet mask? i'm tried to search about network mask and nothing found is it called netmask ? thank you
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Private IP Address Subnetting Standards. How strict are they today?

How strict is this standard today. The 172.16.0.0/12 range is: 172.16.0.0 – 172.31.255.255 Conceptual Config 172.Location.VLAN.Host Location A (10): VLAN 10 - 172.10.10.0/24 VLAN 20 - 172.10.20.0/...
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Possible typo in Tanenbaum's book about NAPT

From what I have understood from multiple sources (web and other books) about the concept of NAPT (also called NAT overload or IP masquerading in Linux environment), if there is a scenario like the ...
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what were the classless routing protocols used with VLSM when it was first introduced?

Since VSLM is supported only by classless routing protocols, if VSLM was introduced in 1987(RFC 1009) and all classless protocol(RIPv2 developed in 1993 , OSPF standardized in 1989 RFC 1131 ) cited ...
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Is TCP's MSL value equivalent to IP's TTL value?

Definition of MSL according to RFC 793: Maximum Segment Lifetime, the time a TCP segment can exist in the internetwork system. Arbitrarily defined to be 2 minutes. Definition of TTL according to ...
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1answer
51 views

Why can my device not get an ip from DHCP in a network with 2 VLANS of which one has DHCP?

In our company we have a CISCO 2811 Switch accompanied by an HP1920 Switch. Our current configuration consists of 2 VLANS: VLAN-2 that has no DHCP in IP range 192.168.0.0/24 VLAN-5 That contains DHCP ...
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Hi! What does it mean if at the same time, two external IP addresses are identical except the last set of numbers, like 123.1.12.16 and 123.1.12.213? [duplicate]

The IP addresses are of two users that are logged in at the same website at the same time. Does this mean the users are on different routers but at the same location or on the same intranet?
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Is the OPTIONS field included in IP checksum calculation?

The source host wants to estimate the time it takes for the datagram to go from one router to another. Therefore, the router uses the timestamp option in IP with Timestamp Flag = 1. I am confused as ...
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Can a Core Switch detect a duplicate IPv4 for two computers not directly connected to it?

I have a Core Switch (routing capability) connected to two access switches. Each switch has a computer connected to it with the same IP and same VLAN. The Core Switch operates as a Level 3 device. All ...
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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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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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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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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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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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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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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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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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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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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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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
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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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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
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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
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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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