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Questions tagged [subnet]

Questions relating to IP subnetting, including planning, calculation and best practices.

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was there supernetting before CIDR or were subnets restricted to their classes

We know that subnetting before CIDR involved sub-dividing classful networks So subnets of class A, B and C. But with CIDR we can have arbitrary prefixes. For example, 192.0.0.0/7. Could we have done ...
user242114's user avatar
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Should a router behind the internet gateway run source routing or masquerading if the gateway router is masquerading?

On a multi-router network, should a router (R2) behind the internet gateway (R1) run source routing or masquerading if the gateway router is masquerading? At this time I can ssh from a host on the ...
wwillfred's user avatar
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What are appropriate filter rules for internet gateway with DNAT? [closed]

Edited with more details: When applying DNAT on a router (R1) that is an internet gateway, and there are other subnets behind it including a router (R2), what filter rules are needed in R2's firewall? ...
wwillfred's user avatar
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What does a byte-boundary mean in this example from Tanenbaum's book on subnetting? [duplicate]

To make CIDR easier to understand, let us consider an example in which a block of 8192 IP addresses is available starting at 194.24.0.0. Suppose that Cam- bridge University needs 2048 addresses and is ...
Don Draper's user avatar
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1 answer
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Nested Network with same IP Space

I have a router (Teltonika RUT) that is connected via its WAN port to a network (let's call it "Big"). The IP Space of the "Big" Network is 192.168.1.0/24 with the Gateway on 192....
bgc's user avatar
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How localhost and its opposite 0.0.0.0 works

Here I am running an application on a computer, host=localhost, the application runs on localhost:5000, or 127.0.0.1:5000. When the computer accesses 127.0.0.0/8, or 127.0.0.0 subnet mask 255.0.0.0, ...
hodini's user avatar
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3 votes
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Computers on different subnets can't talk to each other

I'm teaching an introductory computer engineering course in HS and had students in the lab network together the computers they built in the hardware unit - I appreciate the irony of somebody teaching, ...
Jawsont's user avatar
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What exactly does the term "main network" mean in subnetting?

In the computer networks course, we solve subnetting questions together with the teacher. There is a term we call the "main network". As far as I understand, we fill in this according to ...
Furkan KARADENİZ's user avatar
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How is the number of sub-networks calculated? [duplicate]

I have lately taking interest in networking so I picked up a book to get acquainted with networking principles. The book I have chosen is that of Glen E. Clarke "CompTIA Network+ ...." which ...
Achraf Badiry's user avatar
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VLSM Error on Cisco Distribution Switch [duplicate]

I have created 3 VLANS which should not overlap but somehow are giving me overlapping problems. Any reasons why? Is the switch buggy? VLAN 10 10.1.1.0/28 255.255.255.240 Usable:10.1.1.0 to 10.1.1.15 ...
Xavier Lim's user avatar
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Why is there overlap with two interfaces?

I am trying to configure router0, I assigned ip 192.168.26.1 to gigabitEthernet 0/0 and I tried to assign this ip: 192.168.26.33 to interface serial 0/0/0 but this error appears: 192.168.26.0 overlaps ...
mohdh34m's user avatar
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How can I fit a CIDR subnet at the end of a VLSM /24 network if there is enough space and no overlap? [duplicate]

This may have been answered already here but I am unable to find a clear explanation on this matter. Here is the deal: I am implementing an IP schema for a customer with VLSM. Very simple subnetting ...
humbleStrength's user avatar
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1 answer
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Public wifi router conflicts with company VPN IP address [closed]

I'm a digital nomad and I like to work in cafes and co-working spaces. The problem is that sometimes the network router IP address conflicts with my company's VPN-client IP address. Any and all ...
Nick Bonilla's user avatar
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2 answers
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what information needs a router to make a decision?

How does a router that receives a packet know what to do if it doesn’t know the subnet mask of the IP that sent the packet? The reason for asking this is that I didn't see any field in the IP header ...
netuser2024's user avatar
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1 answer
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Issues expanding subnet from /24 to /21

I've read the posts already here about increasing a subnet and the various possible issues including broadcast traffic. But those examples seem to be a drastic change from a /24 to a /16. What about ...
Desert IT Guy's user avatar
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1 answer
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Network classes vs subnetting/supernetting

I'm studying for my network+ exam and I just had a general question. Since we can subnet and supernet networks, why is there a need to classify them as a,b and c to begin with?
Pokey's user avatar
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How to do IPv6 Subnetting (from left to right) outside nibble boundaries with LAN sizes [duplicate]

Well, up to this point I'm a bit confused of how to do IPv6 Subnetting outside nibble boundaries with specific hosts numbers. Lets say that i have a /64, and that i want to divide it in 3 subnets, 2 ...
MastergGM's user avatar
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IPv4 Address space for PTP links

I operate a relatively small ISP (around 1k households). We have passed the stage where a single router does not cut it anymore. As a corollary, we have to link routers to each other. For this, we've ...
Aloha's user avatar
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What device to use as an intermediary " Wifi Router" for a subnet, plug-and-play architecture?

I am new to network architecture so I apologize in advance for any nomenclature errors. I have 50 IoT devices (running Ubuntu) that I want to stream significant data from. These devices are only ...
Michael Kaca's user avatar
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Do you know any calculatoer where can I calculate dividing of some IP address to several others? [duplicate]

I would like to divide this ip address into 1)First LAN for 10 computer 2)Reserve for 3 computers 3)Reserve for 2 computers I need to know First ip, last ip, brodcast and prefix. Do you know any ...
Mirek's user avatar
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Switch ping to router with trunk port

If I have a switch port trunk directly connect to a router with the follow scenario below: -------- g1/0/1 (Trunk) g1/0/1 |------| |switch| Native VLAN 1 SVI=...
Andrew's user avatar
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Wrong subnet configuration works anyway in a shared bus, but doesn't work in switched lan. Why?

I was told that this configuration (which contains an error in DNS mask which is /23 instead of /24) works only because it's a SHARED bus. If it was a SWITCHED lan, the DNS responses from DNS to A ...
Allexj's user avatar
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about subnetting ip adress 172.16.0.0 [duplicate]

can you explain why we have 172.16.0.0 to 172.31.0.0 so it can't be for example 172.13.0.0 to 172.35.0.0. And also why is 192.168.0.0 and is it possible to be 192.160.0.0? thank you
Giorgi's user avatar
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Outgrowing a /24 network

We have outgrown our 192.168.1.0/24 network. We are ready to replace the router so I thought this would be a good time to expand the network. I've configured plenty of /24 networks but never anything ...
Jeff's user avatar
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1 answer
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Connecting and combining 2 networks

I have networks in 2 separate buildings. Each has its own private IP range. We're installing a private fiber link between the two buildings. Do I just need to adjust the subnet mask so they can see ...
Gary Hanna's user avatar
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2 answers
117 views

Communicating to a device with a random IP, Subnet Mask and Gateway

I think am looking for a way to reliably communicate with devices connected to the network with "wrong" configurations. Our company sells products that can have their network settings ...
nickolaij's user avatar
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2 answers
138 views

Communication with different subnet masks

So I try to explain the dilemma. I have 2 groups of clients and one server. I want these groups to only communicate with the server. This means that each device in these groups should see the server, ...
nub's user avatar
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Is internal network traffic sent to private subnets via their NAT Server?

Similar to this question, I'm wondering how resources in my public subnets communicate with those in my private subnets - when there is a NAT service present. My impression is that a self-managed NAT ...
d8aninja's user avatar
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RIP v2 Network Command

I am comparing the Boson ExSim Lab to the Neil Anderson's Lab on RIP. On one of the labs on Boson ExSim, it asks to configure RIP on the routers, all of which are on some form of a 192.168..0.0/24 ...
Gyd-4nc3's user avatar
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1 answer
80 views

Alternative to the Internet for a local network

Suppose we are designing a network and we want to isolate it from the Internet. Are there any alternatives to the Internet for a local network?
Volpina's user avatar
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3 answers
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If all subnets are a part of same vlan, then the network segregation using subnets does not make sense

This is what we know about subnetting. By dividing a network into subnets, you can separate different departments, locations, or security zones, creating distinct broadcast domains. This segmentation ...
RRHS's user avatar
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1 answer
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Access multiple networks via one managed switch

We have a kind of granulated network structure. At the moment I have two network adapter connected to my system for two of the network areas. The Systems in network A and network B should not ...
MaKaNu's user avatar
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2 answers
87 views

Reach IP in a different subnet

I have two Ethernet devices: One is 10.1.1.10 with a netmask set to 255.0.0.0 The other is 10.255.253.5 with a netmask set to 255.255.255.0 Why can't I reach the second device from the first one (...
Manitoba's user avatar
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1 vote
2 answers
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Is it a thing to subnet an address but still use initial network host?

Hei, Suppose we have 192.168.0.0/24 and we subnet it as 192.168.0.0/25. Is it a normal thing to configure hosts with IP addresses in both /24 and /25 address spaces ? We consider /24 and /25 to be in ...
Iasmina's user avatar
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Is is possible to create a network using supernetting like this? [duplicate]

I need to create a network in the range 200.1.x.x and split it into 3 LANs which consist of 1250, 1750, and 1500 hosts respectively. This network should be able to expand to a total of 56 networks. ...
Tina's user avatar
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1 vote
2 answers
368 views

How does subnetting solve the problem of IPv4 address shortage?

Reading articles on the web, they all say that "subnetting solves the problem of IPv4 address shortage by dividing a large physical network into multiple smaller networks". I do not ...
penguin99's user avatar
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1 answer
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Not able to ping device with different subnet on gateway and ip adress

I am trying to ping a device with IP 192.168.0.200, subnet mask 255.255.255.0. It is configured with gateway adress 192.168.1.1. Is it because the gateway subnet, and ip adress subnet is different i ...
alehol's user avatar
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0 votes
0 answers
19 views

I am getting Confused with host bits and Subnet bits [duplicate]

So i am playing with Cisco CML. I made up a random address 3.0.0.0/8. I wanted to split up that subnet into 4 subnets, So 2^2 = 4. I kinda got confused along the way. In my train of though if we use ...
Eric's user avatar
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2 answers
180 views

GNS3 subnetting and routing

I have a project assignment that consists of 3 routers, the ISP, and 2 company routers, the ISP can address a network /24 IPv4. I delegated a /25 to DNS servers and a /26 to one company and 2*/30 to ...
Tiago Oliveira's user avatar
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1 answer
225 views

Make printer in different subnet accessible to other subnet

i am creating a network and i want the printer which is in a different subnet to be accessible by all other subnets. The router network is 192.168.10.0/24 further subdivided into /28 subnets. The ...
digiadit's user avatar
1 vote
0 answers
63 views

Is there any point to learning about old network address classes anymore? [closed]

It's 2023 and I continue to see people write about IPv4 A,B,C,D, and E networking classes like they still mean something and without saying it's only mentioned for historical purposes. But they are ...
deltaray's user avatar
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1 vote
1 answer
805 views

The use of a link local IPv6 address

In a networking course that I'm following, there was a mention of several ways of how IPv6 link local addresses can be used, such as Assigning the link local address of a router/L3 switch as the ...
Mitrixsen's user avatar
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What are all the reasons for using a separate /31 subnet for a p2p link?

For example in this LAN, the 13.65 and 13.66 are a separate subnet between slip and bsdi, but what is the reason that they have a separate subnet? The only reason i can think of is that bsdi cant have ...
user87014's user avatar
0 votes
2 answers
187 views

Server with multiple NICs takes different route when answering

I have multiple servers which share 2 networks. That is the LAN Network at 192.168.1.0/24, aswell as the Backbone Network at 192.168.5.0/24. ┌────────────────┐ ...
Gandalf1783's user avatar
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0 answers
11 views

How do devices on a network communicate when they are only connected through a router? [duplicate]

This is in my router's routing table: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.1.0 0.0.0.0 255.255.255.0 U 0 ...
imnglwhatheheckw's user avatar
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0 answers
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Variable Length Subnet Mask with two hosts [duplicate]

I started learning subnetting and i encountered some problem involving Variable Length Subnet Mask and which problems i encountered so far is it just specify a specific number of host per subnet but ...
ILoveGrapes's user avatar
2 votes
1 answer
106 views

Mask for sending network packets

When sending packets in a network, do the PC's all have to share the same subnet mask or can you dedicate comps to mask addresses? I am wondering if this also determines collisions and if it is a ...
aitía's user avatar
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1 answer
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Routing question

Let’s say I have router A and B and a subnet 192.168.10.0/24. Can I use part of that subnet as a connector between router A and router B (ie. 192.168.10.0/30, .1 on A and .2 on B) and have a route 192....
mitch's user avatar
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1 vote
1 answer
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What is the Logic of AND and OR operations in subnetting?

To calculate subnetting for given IP address and the subnet address, we do AND operation first to get the network address and the first usable IP address of the subnet. Why do we use AND? I know it ...
Red And Black's user avatar
0 votes
1 answer
102 views

While VLSM subnetting, will there be a case that addresses are insufficient? [duplicate]

Note-:Here, IP address means IP address+subnet mask. I am studying network design. My question is will there be a moment where you choose IP address for subnetting but turns out finally that it's ...
el_waleou's user avatar

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