Questions tagged [subnet]

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

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IPs that don't have subnet mask

I'm new to networking. I know that some IPs don't have a sub net mask like 127.0.0.1 and the range that starts with 127. I wanted to know if there is any other IPs that don't have sub net mask.
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Two routers on the same subnet - Possible issues?

What issues can occur when two routers are set to the same subnet (no cascading, both cable connected to the same switch)? For instance: - LAN: 192.168.1.0/24 - Router A: 192.168.1.254 - No DHCP, ...
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What is the last usable address in an IPv6 network

IPv6 does not have broadcast, so is the last address usable? Besides it being long, is it bad practice to actually use it? For example: A:B:C:D::0/64 starts with A:B:C:D:0000:0000:0000:0000 and ends ...
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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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Additional subnets in a class C IP [duplicate]

If i'm designing a new subnet mask for a class C IP that will have 5 subnets that means I need to borrow 3 digits since 2^3-2 > 5. My question is, how many additional subnets do we have? would it be ...
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Subnetting for this question, please? [duplicate]

As a Network Support Engineer, you are tasked by your Supervisor with assigning IP addresses for your new MAN( Metropolitan Area Network) which consists of seven (7) different branches, each branch ...
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Split a Netmask into little chunks [duplicate]

I would like to know how I could divide a Netmask like 255.255.255.192 in 8 parts. Would it be something like this: 255.255.255.192 255.255.255.128 255.255.255.0 I'm really confused.
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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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4answers
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Multi LAN network does the main router to the internet need to be in its own subnet?

I have to design a network where there are 4 within which are different number of VLANs with varying number of hosts per VLAN depending on the building. My confusion lays in the main router, does it ...
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2answers
37 views

What is the suitable private IP? [duplicate]

What is the private IP that I may use if I am about to subnet a total of 743 hosts in my office? Should I use 10.x.x.x, 172.16.0.0 - 172.31.x.x, 192.168.x.x or all of them are allowed? Also if more ...
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Does 10.10.192.0/20 represent the same number of address with 10.10.195.0/20 [duplicate]

I knew 10.10.192.0/20 can represent the ip addresses from 10.10.192.0 to 10.10.207.255, but I'm confused how does 10.10.195.0/20 represent? I guess it is same with 192.0/20 right?
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CIDR notation confusion [duplicate]

So we are using CIDR for subnetting In that we just define the subnets by using / SO my question is if I am using /24 it means that I have the last octet for host. But if we use anything from /17 to /...
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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
194 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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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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40 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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2answers
55 views

Why does the host machine need subnet mask? [duplicate]

The routers require subnet mask to route the packets to other routers or hosts, but why do host machines that are not routers such as computer running Ubuntu or windows need subnet mask to be ...
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246 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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Whats the proper way to write subnet size with / notation?

If I need to write a Subnet mask in /x notation, would it be correct to take the subnet id/X or the broadcast ip/x? I.e. for a 256 IP subnet: 10.10.0.0/24 or 10.10.0.255/24?
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261 views

Are subdomain and subnetting related concepts?

Recently while trying to grasp some basic networking concepts - I felt subdomain and subnetting are related concepts and wanted this group to confirm and add more insights on this. I understand that ...
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VLAN based subnets, where should I untag a VLAN?

I have attempted to search this problem but I don't really know how to explain it properly (possibly a sign I've taken on more project than I can handle). Anyway I am currently working on chopping ...
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How does a host in one subnet know to forward the packet to the router MAC, when trying to send a packet to another subnet

I am trying to understand the ARP protocol and I could not understand the above. Consider the topology as follows: H1(1.1.1.1) - (1.1.1.0)R(2.2.2.0) - H2(2.2.2.2) My understanding is that if the ...
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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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Why is this subnet config required by my vlan “snake topology”?

I must validate the bandwidth on all 8 ports of a switch. We intend to do this with a "snake" topology as described in this article: http://thenetworksherpa.com/test-throughput-alchemy-using-a-snake-...
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Can a single subnet work across several switches?

New to networking and studying hard but limited access to a kit to try things at the moment... My question is - if I had, for example, two Layer-2 switches cable connected, could I have devices on ...
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1answer
221 views

Sonicwall: force all traffic from specific source through VPN

We have a main office (M) with a Sonicwall TZ215, and a branch office (B) with a TZ210. Computers in B access the server in M through a site-to-site VPN between the two Sonicwalls. Internet traffic ...
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483 views

VLANs vs subnets pros and cons

What are the pros and cons of designing an entire network using VLANs rather than design the network only using subnets?
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CIDR and VLSM what are the differences?

CIDR improves the allocation of IP addresses. VLSM allows to define a subnet as we wish. Can CIDR used without using VLSM?
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How is traffic correctly routed in Site-to-Site VPNs where all sites are on the same subnet?

http://rockhoppervpn.sourceforge.net/ref_site2site_bridge_6.html The diagram on this page shows all 3 sites using the same subnet, 192.168.0.0/24. Let's say on the hub site where 192.168.0.10 is the ...
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Can only same-sized networks be combined? [duplicate]

On multiple channels a "rule" is that only same sized networks can be combined. But this is only a valid constraint, if the subnet mask needs to remain the same as of the nets to be combined, correct? ...
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How to calculate subnet mask including, network address, gateway, broadcast address and host range? [duplicate]

You are defining network boundaries within a /24 network of 172.30.20.0/24. Please complete the segmentation of the /24 to account for multiple smaller networks of 115, 50, 28, 12, and 5 hosts. ...
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Split to four equal size subnets [duplicate]

Question; Suppose an ISP owns the block of addresses of the form 128.119.40.64/25. Suppose it wants to create four subnets from this block, with each block having the same number of IP addresses. What ...
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About relation of ip adresses and number of hosts [duplicate]

Question is; https://imgur.com/9nKqRgE I am not sure about the answer but my thinking is that if there are 35 hosts then 2^x=>35 after that i find x is 6 it means 6 zero we have on subnet. and ...
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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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ARP traffic for devices in same LAN but different subnets [duplicate]

Given a LAN with 5 devices (a,b,c,d,e). Where devices a and b are in one subnet and d,e,f are in another. Will an ARP request broadcasted by a looking for device b reach devices d, e ,f as they are ...
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How to calculate bits needed for host, bits left for network, number of available networks? [duplicate]

I have a class b address of 145.14.0.0 I need to create a scheme where each subnet accommodates 2259 hosts. can someone explain step by step how to do that
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TTL And Wildcard mask

I have two questions that i wanted to ask before. What is TTL?! I know that it's time to live for packet to die it count how many hops you jump in it every icmp but i don't know how it works and what ...
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6answers
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packet routing between subnets on same vlan

I am trying to understand how packets are routed within the same VLAN. I understand that typically there should be a 1:1 mapping between VLANs and Subnets. However if i deploy the following ...
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3answers
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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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2answers
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Is the first address in an IPv6 subnet assignable?

I am working in a lab and have configured a series of /125 subnets between routers. Lets ignore the best practice for this discussion of using /64 for everything. When I assign fd00:f9a8:ffff::257 to ...
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1answer
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how to get the smallest summary route? [duplicate]

i am practicing subnetting, then i got this question from the web. then the answer showed up as 172.16.0.0/12, i am puzzled right now how did that happen. please if anybody out there can explain to ...
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1answer
133 views

How to interpret subnet mask [duplicate]

I received a datasheet with which I need to configure a server that doesn't do dhcp but rather needs to use a static IP address. The sheet tells me to set the subnet mask 255.255.252/22. I tried to "...
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3answers
682 views

Cisco ASA 5512X does not allow connections across VLANs to internet

First time doing a network, I'm a software guy normally. I am setting up a network to share and internet connections to multiple properties. The goal is to segment each property onto its own VLAN. I ...
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216 views

How does aggregate routes behave in BGP?

If a router received two BGP updates for the same prefix and both these updates are aggregate paths how do the router decide which one to take? Let us say that it needs to decide based on AS Path ...
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4answers
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Why is 10.1.255.255 an invalid broadcast address?

I’ve been following the CCENT official certification book(100-105) and came upon this question in the “do I know this already?” quiz. The books only covered /24 subnetting only so far. Which of the ...
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2answers
71 views

Different Wi-Fi security levels under same private subnet

I'm working on an assignment and I'm given a hypothetical scenario where: A company has a local subnet where everything shares the flat address space 192.168.0.0/8 (this means that any device can ...
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1answer
46 views

VPN to a current subnet ID

I am sure this is a fairly basic question, but the standard google searches have not told me what I am looking for. I have a restaurant that uses an ipad point of sale on a dedicated subnet id: 192....
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3answers
129 views

Bridges, hubs, switches and repeaters in subnetting

I'm learning to subnet and I'm constantly doing exercises on paper about this topic. I'm trying to breakdown a network into smaller subnets, given the number of hosts for each one. For now, I only ...
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1answer
196 views

Different sized subnets [duplicate]

I am not sure the wording to search for and therefore this question has probably been answered before and i just cant find it. I am puttiing together a small WAN and im using /29 addresses for the ...
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2answers
48 views

Can 2 Directly connected PCs having the same network ID but different subnet mask talk? [duplicate]

If Pc1 has IP 192.168.10.2 / 24 ---> Network ID : 192.168.10.0 and Pc2 has IP 192.168.11.3 / 23 ---> Network ID : 192.168.10.0 directly connected (no switches no routers). Why cant i ping? But if ...

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