Questions tagged [ipv4]

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

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1answer
135 views

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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3answers
67 views

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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1answer
215 views

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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1answer
157 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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1answer
49 views

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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8 views

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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1answer
73 views

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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3answers
80 views

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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3answers
92 views

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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1answer
132 views

"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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3answers
91 views

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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2answers
133 views

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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1answer
34 views

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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2answers
547 views

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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1answer
6k views

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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1answer
36 views

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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1answer
170 views

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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1answer
48 views

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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0answers
12 views

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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3answers
2k views

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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2answers
40 views

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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5answers
2k views

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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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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1answer
44 views

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
39 views

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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2answers
84 views

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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2answers
39 views

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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1answer
182 views

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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4answers
161 views

Private IP Address Subnetting Standards. How strict are they today? [duplicate]

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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2answers
60 views

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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1answer
88 views

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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2answers
516 views

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 ...
2
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1answer
102 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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1answer
39 views

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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1answer
192 views

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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2answers
238 views

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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2answers
63 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
62 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
37 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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2answers
220 views

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
29 views

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
6k views

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
243 views

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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2answers
211 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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0answers
45 views

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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4answers
697 views

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
192 views

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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0answers
20 views

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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