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-2
votes
1answer
31 views

SOHO Routers and Non-Standard CIDR Blocks [closed]

I recently learned about private networks. From what I understand there are three address ranges for use in private networks: 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 If this is the case, then why ...
-4
votes
2answers
104 views

Exercise regarding public IP address and its “class C” [closed]

An exercise I am doing asks the following:- Identify what your public IP address is. Using public information sources, see what you can learn about your IP. If you don'ʹt find anything on your ...
2
votes
2answers
252 views

Why does the Cisco RV180 not let me use a 255.255.254.0 subnet mask with a 192.168.2.1 LAN IP address?

I'm a Sysadmin for a tech company. We have a Cisco RV180 gateway device. We are at our breaking point for IP addresses, so we are changing from a /24 to a /23 subnet to allow for double the devices. ...
0
votes
1answer
119 views

Using a CIDR range as a Routed Subnet?

I have a /29 subnet assigned by my ISP, with an SonicWALL office router and a Cisco voice router hooked up to a 'net-rail' of sorts with untagged VLAN switch ports connecting my ISP router's output ...
1
vote
2answers
110 views

How to reserve first 32 hosts in IP address range

I am using NoDogSplash which is a captive portal, meaning it redirects your packets and forces you to authenticate before you can access the Internet. It does this in an isolated 10.0.0.0 network. ...
2
votes
2answers
545 views

How do I divide a network into smaller subnets using a single Layer 3 switch?

I have had trouble searching for help on this one, as most searches for VLSM, CIDR and layer 3 switching bring back very basic questions posted by students just starting their CCNA. I have a batch of ...
4
votes
2answers
158 views

Is this IPv4 and subnet combination public or private? [duplicate]

Possible Duplicate: How does IPv4 Subnetting Work? I thought I understood this but I am momentarily confused. Here is an example: Are all IPv4 addresses from 192.168.0.0 to 192.168.255.255 ...
3
votes
0answers
153 views

How to support VRF in Netflow Collector?

I am somehow able to analyze netflow packet using my own netflow collector (build in python). It works for certain ip and CIDR(Classless Inter Domain routing), definitely not overlapping. What is the ...
1
vote
2answers
110 views

smaller CIDR network on larger Class C network

I have a network: 192.168.31.0/24 and computers on the network have static IPs 192.168.31.* I'd like to segregate 5 of those computers (say 192.168.31.201 - 192.168.31.205) and put them behind a ...
6
votes
2answers
779 views

Grepping for CIDR ranges

From time to time I want to grep CIDR ranges out of my Apache log files. This is easy for ranges that fall on the natural boundaries (/8, /16 and /24) but not so easy for other ranges such as /17 and ...
3
votes
1answer
755 views

Subnetting into 6 CIDR/24 network and 2 CIDR/27 networks?

I am revising some questions for an exam and one of the questions was provide the ip numbers and a diagram for a company which has 3 branches. Paris/Berlin/Cairo (random locations I know) Now I belive ...
6
votes
1answer
629 views

If I change a router's subnet mask to one that includes the old one, will the hosts with the old configuration still work?

Currently I have a router that is addressed as 10.2.1.1 on a 10.2.1.0/24 network. All of my hosts have default gateway 10.2.1.1 with mask 255.255.255.0. I want to know: if I change my router to ...
0
votes
3answers
2k views

A Way To Determine IP Range From CIDR? [duplicate]

Possible Duplicate: How does Subnetting Work? Is there a formula or a calculator for determining an IP address from CIDR that I was given: 38.103.17.160/27? I would like to know the ...
1
vote
1answer
216 views

Openvpn: iroute for all theoretically reachable [public] IPs

I am testing the creation of an enforced default route of only public IPv4 space via OpenVPN. OpenVPN does not support 'iroute 0.0.0.0 0.0.0.0' out of the box, because it contains code that rejects ...
7
votes
4answers
643 views

CIDR Ranges for Everything except RFC1918

I'm looking for a list of CIDR blocks for "The Internet", i.e. everything from 0.0.0.0 to 223.255.255.255, excluding RFC1918 address space of 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 (yes, I know ...
1
vote
2answers
534 views

Can I divide a /28 network into two /29 networks?

I have a 192.168.1.64 /28 Network Can I divde this network into 192.168.1.64/29 and 192.168.1.72/29 ? My Question is related to the fact that now the "network address" (192.168.1.64) of ...
1
vote
5answers
3k views

Can't authorize a server for Amazon RDS

We are attempting to slowly migrate a website over to AWS among other things. We decided the first thing to move was the database. We have some dedicated server with a different hosting provider. We ...
4
votes
2answers
584 views

Reverse DNS Delegation from ISP

I get a /29 Delegated to me from Verizon(Fios) and I got them to delegate rDNS to my Name servers, I Notice that with some systems that it works and is able to get my PTR record, but on some it isn't ...
0
votes
1answer
75 views

subnetting a class c on a cisco 3825

I have a class C that I want to better understand before I implement a change. Right now, ip address 192.168.0.1 255.255.255.192 ip address 192.168.0.65 255.255.255.240 secondary So, where is ...
1
vote
6answers
202 views

Trouble subnetting a network

I have the network address 160.80.0.0/24 and have to subnet things like this: How would I subnet this network to accomodate such a huge number of hosts? :D Any guidance for a newbie? I've already ...
0
votes
6answers
311 views

Is there a tool for subnetting for free?

I'd like a program that I can write in an IP address and give it the Subnet mask and have it divide the networks in C level networks. Thanks. Something that I can download please, not a website.
1
vote
2answers
280 views

How to determine largest cidr in a range of IPs

Say I've got a begin ip and an end ip. What would be the easiest way to figure out the largest cidr I could allocate from this range in order to reduce fragmentation? For example, I have the range ...
4
votes
1answer
24k views

What does 192.168/16 mean? [closed]

OK, this isn't really a server question in practice, but I'm pretty sure it has something to do with server management. What is this joke supposed to mean?: http://xkcd.com/742
3
votes
3answers
2k views

13 IP addresses, how to add them to domain SPF?

Let say I have these IP addresses on my server: 170.120.210.209 gateway 170.120.210.210 server IP 170.120.210.211 170.120.210.212 170.120.210.213 170.120.210.214 170.120.210.215 170.120.210.216 ...
3
votes
1answer
145 views

Is it safe to assume that two hosts on the same /24 network belong to the same AS-number?

Assume two IP-addresses in the same /24 network (say 1.2.3.*): 1.2.3.X 1.2.3.Y Is it safe to assume that these two hosts belong to the same AS-number? If not, roughly how often is that the case ...
5
votes
4answers
2k views

Linux Command line tool to work with netmasks / CIDR notation

I'm terrible at working out network subnets in my head. Is there some command line tool for linux (ubuntu packages a plus), that lets me put in 255.255.255.224 and it'll tell me that is a /27?
2
votes
1answer
2k views

How To Add Multiple /24 Network IPs in Ubuntu

We have a client who needs to set up 2 Class C (/24) address ranges in Ubuntu. We have a single nic connected to the switch currently and the IPs are set up at the switch. We have done this many ...
17
votes
4answers
9k views

Reverse DNS in a CIDR world

Reverse DNS seems to be strongly tied to class boundaries, what methods exist now that CIDR is the standard to delegate authority for a subnet? If multiple methods exist which one is best? Do you ...
21
votes
6answers
7k views

CIDR for Dummies

I understand what CIDR is, and what it is used for, but I still can't figure out how to calculate it in my head. Can someone give a "for dummies" type explanation with examples?