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Questions tagged [ip]

For questions about Internet Protocol (IP), an OSI layer-3 network protocol. There are two current IP versions in use: IPv4 and IPv6.

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19
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2answers
5k views

What is the difference between 0.0.0.0 and a loopback IP address?

From the book Computer Network: The IP address 0.0.0.0, the lowest address, is used by hosts when they are being booted. It means ‘‘this network’’ or ‘‘this host.’’ ... All addresses of the ...
1
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3answers
120 views

Is an IP address assigned only to something with a Mac address?

From https://en.wikipedia.org/wiki/IP_address An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol ...
7
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1answer
1k views

Dealing with IP Spoofing

Border routers, which are routers that span two or more sub networks, can be configured to block packets from outside their administrative domain that have source addresses from inside that domain....
2
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2answers
145 views

How does a router know the destination mac?

so if I send a packet from a host to another from the same network we know the mac address of both the source and destination. However if the receiver is in a remote network the destination mac ...
2
votes
1answer
51 views

Can mobile devices take a global IPv6 address by means of only routing?

I'm probably asking this the wrong way, but here it is; I have a /48 block with static addresses for every device on the network. Everything is routed, no NAT, no tricks. My question is: on a mobile ...
1
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3answers
2k views

My first IPv6 ping fails

I have some dual stack websites. When I open my websites they connect using IPv4 the first time, and then IPv6. If I ping the IP address directly, the first ping fails for IPv6 and then works fine. ...
3
votes
3answers
447 views

Is it possible to perform a Layer 2 (MAC address) traceroute?

I understand the difference between layer2 & layer3 and MAC & IP. I understand address resolution protocol, etc. But is there any way to do a traceroute that will show Layer 2 information? For ...
-1
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1answer
47 views

Network IP questions [duplicate]

Suppose I have a network with IP address 192.168.10.1/16. This network can hold up to 65536 machines, from 192.168.0.0 up to 192.168.255.255 (65534 machines without the network ID and broadcast ...
0
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2answers
86 views

Why we need ARP when each device has its own IP address?

I don't really understand Address Resolution Protocol (ARP). Why we need ARP when each device has its own IP address?
5
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3answers
3k views

Cisco Switch (Cayalyst 2960-X): How to add a rule to the access list that filters out l2tp packet when a specific MAC address appears in it?

I am using a Cayalyst 2960-X series Cisco Switch, Whose 2 SFPs are connecting between 2 hosts (A,B). A,B are connected to the switch's 1,2 ports respectively. The host communicates using an l2tp ...
3
votes
1answer
45 views

Why aren't we encrypting data on Network level instead of transport level when using e.g. HTTP [closed]

Why we are bothering to encrypt our data on a transport level, instead of just doing that on a network level with e.g. IPSec and get rid of the need to to that in upper layers. For example instead of ...
0
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0answers
32 views

Why are there only ~4 billion IP address available? [duplicate]

I am new to networking, so I apologize is this question is naive. I understand that 2^32 = ~4 billion. However, if you add in subnet masks, won't this number increase? For example, let's say you have ...
0
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1answer
55 views

Usable IP addresses and MPLS

I work at a company where I am partly responsible for IT, just because I'm semi technical and we're not big enough to warrant a dedicated role for someone else. I was asked to look into upgrading out ...
-1
votes
1answer
70 views

Classifying IP address [duplicate]

I need to decide if the IP address 130.192.0.0 is a host or network address and which class it belongs to (A/B/C). I've read about the different ranges that the different classes have of IP ...
2
votes
2answers
1k views

Cisco 899G-LTE Cellular 0 interface in spoofing mode

I have a problem. After I've reseted my router configuration it doesn't get IP from LTE SIM card. Seems like my celullar0 interface is in spoofing mode. > Router#show interfaces cellular 0 ...
-1
votes
2answers
288 views

Is IP address starting with 115. public or private?

I have one device with ip address 115.124.114.111. I want to know if IP address starting with 115. public or private?
1
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2answers
5k views

How do routers traverse packets to their destination?

Sorry in advance for such a noob set of questions. I understand that when set with the task of sending a packet to its destination, a computer first checks that the IP address of the destination is ...
1
vote
1answer
43 views

Exclude 10.63.128.0 10.63.255.255 or 10.63.128.0/17 range from 10.0.0.0/10

Please help to suggest a method to exclude IP range 10.63.128.0 10.63.255.255 from 10.0.0.0/10. I have a access list 3100 to filter the traffic with rule 10 10.0.0.0 0.63.255.255 and now I have to ...
0
votes
1answer
190 views

Finding the IP address of a Cisco 3750G

Hello i have a Cisco 3750G switch and i need to find the IP address and I dont have a serial cable, so I need the IP address to login into the web-interface. Does it need to be connected to a network? ...
0
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0answers
19 views

DHCP Broadcast messages [duplicate]

Why are there so many DHCP broadcast messages while trying to give a computer some network settings? 2.Last,when can these broadcasts be avoided and how are DHCP relay agents related to the whole ...
2
votes
2answers
1k views

0.0.0.0/32 Special-Use address

I was wondering what is the role of this special-use address. The similar 0.0.0.0/8 represents a host with no IP assigned,but it's not the same with the 0.0.0.0/32 address What is the difference?
3
votes
2answers
252 views

Subnetting-Supernetting and Classful-Classless routing

1) Subnetting and Supernetting can both be done for private and public IP addresses? 2) Classful addresses weren't successful because of IP wasting, and that is why the 'network mask' was invented, ...
0
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1answer
311 views

Private IP vs MAC

What I know is that when we connect to another IP, our Public IP gets shared to the outside world, and when they address us they use our Public IP (gateway), and then the gateway directs the ...
1
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1answer
596 views

Add a router with dhcp to existing lan and create a secondary private network [closed]

I'm not a network guru. I have had this scenario a few times at a hackathon or small event for technical people. There are usually a group of 50-200 but with an average of anywhere up to 4 devices per ...
1
vote
1answer
355 views

What are the component names of CIDR Prefix Notation?

What are the components of the IETF's CIDR Prefix Notation called? 172.16.0.0/16 contains two parts: 172.16.0.0 /16 In the RFC the entire term 172.16.0.0/16 is defined as the "Prefix Notation" for ...
3
votes
2answers
300 views

How does a TCP segment fit into a smaller IP packet?

The IP protocol can handle fragmentation and it includes the fragmentation offset and identifier. I know this comes into play when your IP packet is too big for some specific network or link where the ...
22
votes
6answers
6k views

What stops someone from configuring their network with IP addresses they do not own?

Here's the scenario. I was picturing a university that bought a range of IP addresses. I think they'd still be inside a ISP (right?), but they'd have freedom to configure stuff the way they wanted. ...
0
votes
1answer
60 views

IPv6 variables or other methods of shortening

From the dawn of when I heard about IPv6 many years ago, to my continued hesitance to make good use of it in today's world where it's eventually going to become necessary... my biggest issue I think ...
12
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8answers
6k views

Why are IP addresses given to each interface and not device? What would the implications of that be?

Why do we need to give IP addresses to each interface? Wouldn't giving one to each device be enough?
1
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3answers
807 views

In IPv4 does the identification field in a TCP packet change for fragmented packets?

If a TCP packet is fragmented then would the identification field of the header stay the same for all of the fragmented packets, or would it increment by 1 so that the receiver would know what packet ...
2
votes
2answers
151 views

Broadcasts in IPv6

I'm aware of the fact that broadcast has been removed from IPv6 and just has multicast instead. However, recently I read "This process (ARP) is now achieved via a multicast address called the ...
4
votes
1answer
16k views

Assign an IP to a MAC Address to DHCP POOL

The idea is that I want to have a static IP for the MAC computer always assign me the IP . please help , as would the commands ? I have a cisco 3650 switch core where I configured the DHCP and VLAN ...
2
votes
1answer
241 views

IPv6 - RA prefixes and flags

I'm trying to understand how SLAAC works, but having troubles understanding how the information inside the Router Advertisement is used by a client. Let's say neither the Manager nor the Other ...
2
votes
1answer
1k views

Are there public servers with a 192.168.X.X IP address?

I was wondering about the IPv4 problem and thought about one of the solutions where endpoints do not have their own public ip address, but rather an address only used within the VPN and a mapping by ...
2
votes
2answers
1k views

Connect to switches with the same IP

We used to have one site with one Cisco switch to which a RANCID server was connected to take configuration backup. A new site was opened, and we have another switch on this new site. The sites have ...
4
votes
5answers
11k views

How many IP addresses can a device or an interface possess?

Can one IP address be assigned to more then one device or interface? In which situations may this happen? Can one device or interface posses more than one IP address?
4
votes
1answer
650 views

What is the point of a subnet mask on a local network?

I have a question regarding subnet masks and my understanding (or misunderstanding of them). So when a subnet mask is used, a bitwise AND is performed using the subnet mask and the IP address(es). ...
3
votes
3answers
6k views

Network setup for multiple devices with the same IP

Because I do not find the correct question that I can ask google, due to the lack of terminology. I'm trying to ask it here. Please have patience. My Question is similar to the questions asked here ...
1
vote
2answers
327 views

How are packets routed based on IP and how are those routes acquired?

Good day all, this is my first question here, be gentle in judgement Background: At university, we are covering Network Routing Protocols. Having possibly found 2 issues with current routing ...
1
vote
1answer
414 views

UDP and fragmentation calculation

Assume we have a ethernet link with an MTU of 1300 bytes, while an application want to send 5200 bytes of data. How many fragments do we transmitted ? i would say 5, to send 5200 bytes over a link ...
7
votes
2answers
126 views

VLAN clarification

I've inherited a network with approximately 200 computers and no VLANs configured. We are currently adding a system that uses multicasting to communicate with each other and will be adding VoIP in 2 ...
3
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2answers
9k views

Mac address and IP address in physical addressing in Data-Link layer

Framing is done in Data-Link layer. We give physical addresses there. Destination address, source address and MAC. If two PCs in different networks, we try to sent data from one another, we specify ...
2
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4answers
5k views

Does every subnet have broadcast and network addresses?

Given /26 subnets for a /24 network: Subnet 1 0-63 Subnet 2 64-127 Subnet 3 128-191 Subnet 4 192-255 Does every subnet have its own network ID and broadcast address? Meaning: Subnet 1 0-63 (...
1
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2answers
827 views

Is my dynamic IP address provided by my ISP shared?

The IP address provided by my ISP changes. I want to know if it is shared by someone else in this world.
2
votes
2answers
2k views

What is the difference between MAC and İP broadcast addresses?

As far as I know, they are both used to send a packet to all hosts that are connected to a local arena network. Why would anyone need two addresses to send a broadcast package?
1
vote
1answer
150 views

Clustered Juniper devices using public DoD IP addresses for communication?

Ok, so I have to admit I am not an expert in how Juniper networked devices work, so this entire issue might be why I am having issues understanding something I am seeing on a pair of clustered SRX210H'...
2
votes
2answers
482 views

IP Fragmentation

When Device A sends an IP datagram toward Device B, the IP Layer of Device A computes if it must or not fragment the IP datagram to fit the link MTU. Sent to the next hop, the process will be repeated....
1
vote
1answer
426 views

Help setting up multiple IP ranges on same subnet

So long story short. We setup our network YEARS ago, when we were a small company of only 10 people. Now, we are pushing 100 employees, and my network has outgrown itself. Originally, I setup the IP ...
1
vote
2answers
132 views

What does it mean if an Ethernet Card has two RJ45 ports?

Ethernet is below IP in the OSI model. But how is an IP address actually assigned to an Ethernet port? I know, that Ethernet has nothing to do with IP, but under Windows I can assign an IP address ...
3
votes
3answers
340 views

Is it ok to leave the trailing 0's off in IPv4 CIDR notation?

In IPv6, we can collapse 0's when talking about addresses. In IPv4, can I write 192.168.1.0/24 as 192.168.1/24? Can I write 10.0.0.0/8 as 10/8? I'm working on some software that takes CIDR's as ...