Questions tagged [ipv4]

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

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2
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2answers
199 views

What happens at the destination end if it is in a WAN?

When the Sender gets to know that the destination is in a other network ( by doing the AND operation with the subnetting adress of its network ) what are the procedures followed, so the packet does ...
9
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2answers
6k views

why TTL value 1 in IGMP

why TTL value 1 in IGMP protocol and what are the different values possible in TTL section for Multicasting. What I got from the google is that if TTL value is 1 then it won't leave the LAN, but if ...
5
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1answer
2k views

ASA 5505 Assign Outbound IP to VLAN

I have a Cisco ASA 5505 running 8.3.1 software. I've setup my VLANs, and I have a block of static IP addresses. One IP address is set as the 'outside' interface IP address, and I have a static route ...
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6answers
27k views

How are IP addresses mapped to MAC addresses?

I've been reading about the differences between MAC and IP addresses, and why we need both of them. To summarize, MAC addresses are physical unchangeable unique IDs for every single device while IP ...
3
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4answers
8k views

When it comes to Computer Networks, what is a logical address and physical address?

I understand the concept of logical address, and physical address when it comes to computer memory. That is, physical is the actual address and logical address is what the applications think the ...
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4answers
607 views

Aren't MAC and IP doing the same job?

The question "What is MAC for?", "What is IP for?", and even "What is the difference between MAC and IP?" have been asked many times, even on these forums. Yet, there is STILL no clear explanation, ...
5
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5answers
541 views

Is there a way to find out if a specific device is a router?

I am working on a small project that creates a map of your local network and I need to be able to determine if X.X.X.X is a router or a device connected to it. My original strategy was to use nmap ...
5
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3answers
901 views

In networking, is there a word for the first n bytes of an IP address?

I have two IP addresses. They share an IP address to the nth byte. Is there a word that effectively says that they have the same IP address up to the nth byte? Are there different words depending on ...
18
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6answers
8k views

Why use IP if we already have a MAC address?

I am preparing for ICND1 exams and recently started to learn about different Cisco devices. I have just come to know how the packet is generated to be transmitted over a network, or outside the ...
10
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1answer
7k views

If two NICs are bonded and connected to different switches how does a router decide which switch to forward the packets to?

I am trying to understand how the architecture works in case of NIC Bonding. The scenario is: There are 2 NICs on the same system. Both are bonded to support failover and load balancing. Hence the IP ...
28
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4answers
14k views

What is the proper term for ipaddress/hostname:port

What is the proper term for (example) hostname.tld:433 (hostname:portnumber)? It is not just hostname, and it is not really a URL either :) same goes for 10.0.0.1:3306 etc.
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4answers
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IPv4 shortage is now becoming a reality - what is needed for IPv6 to work?

Today I read that Microsoft has no more IPv4 addresses for its Azure cloud. Earlier this week I read that Latin America is out of IPv4 addresses as well. These are real - not predicted - IPv4 address ...
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4answers
423 views

60 devices on a /29 network

My company asked me to set up a network with 60 devices (all have MAC addresses and use IPs, but they are not all computers), there is a 3rd party company that will maintain the network. They are ...
2
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3answers
3k views

MTR packet Loss at intermediate hop

We are currently having issues with our WebService being intermittently inaccessible to clients. During diagnosis with the NOC and with some internal testing we believe we have a router dropping ...
3
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1answer
2k views

L3 Switch Static Route for 2 gateway

In my network I use L3-3650x as core switch to route internal network. I have 2 internet gateways, one for local internet [192.168.2.1] and the other for Japan connection [172.17.138.1]. Both routers ...
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1answer
1k views

assigning Highest IP on each subnet is the default gateway to cooresponding VLAN

Network Diagram: I got 3 vlans 1st Management Required hosts: 15 Network ID: 192.168.100.0/27 Range : 192.168.100.0/27 - 192.168.100.31/27 Highest IP default-gateway: 192.168.100.30/27 2nd ...
10
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1answer
3k views

How does NAT share one public IPv4 address across multiple private IPv4 addresses [closed]

I think it's a very classical question, but, thought I've have some background, I don't have enough vocabulary anymore to search and understand correctly in the Web. Let's say I have a home network ...
0
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1answer
1k views

Calculate subnet mask [duplicate]

I'm a student of electronics and get lessons in networking as well. But on one of my tests I got the question: What subnet mask is indicated by the network address 172.16.4.8/18? I know the answer ...
4
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3answers
3k views

Static IP's vs DHCP from management standpoint

I was recently graced with a new job opportunity in a large higher ed NE department. This is my first job working with a large network of several thousand users. Throughout my education, I followed ...
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3answers
2k views

Determining the network class of an IP address [duplicate]

How do you determine the network class of an IP address? For example, I have the IP address 127.0.0.1
6
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2answers
16k views

Why we need IP address on LAN if switches can't read IP addresses

A beginner question: Why we need to assign IP addresses on LAN if switches are not able to read them? Because of ARP (Address Resolution Protocol)? But Switches can't send ARP requests (switches can't ...
0
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1answer
229 views

Calculating Netmask address in specified range [duplicate]

how can I find Net mask address in the rage: 192.16.128.0 to 192.16.135.255 Note: I want to use Classless Inter-Domain Routing so net mask should not be multiple of 8. what should we calculate it for ...
33
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3answers
8k views

Why are IPv4 addresses 32-bit?

Many moons ago, when I was just a wee bairn commencing my career, I had a job interview for a low-level developer role. Having at that time just learned how CIDR was implemented, I was keen to show ...
8
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2answers
7k views

Duplicate IP Address Prevention?

Yesterday a laptop crashed the network because the IP address of the computer was the same as the router. Computers in the network were reaching the laptop instead of the router. Is there anyway to ...
6
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2answers
586 views

VLAN-Subnets 1:1?

I often hear people saying that each VLAN is a subnet (or is associated with a subnet) but is that really true? Assume I have 10 big offices. I will have a subnet for each office but only 2 VLANs ...
3
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3answers
848 views

How fragmentation works in real world

I have one example scenario, let consider i am sending 1500 bytes of frame over the internet. which is passing through 576 bytes MTU capable router. My question is, Is that router will do the ...
7
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4answers
19k views

What is Null 0 interface?

In which case is ip route 10.1.0.0 255.255.255.0 null0 used? Thanks in advance. This question is a repost of the same question in The Cisco Learning Network; however, the answers are unique to ...
2
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3answers
748 views

What is IP address management ? Why its needed ? How does the vendors like Bluecat Networks and Infoblox solves the IPAM problem? [closed]

Recently I heard a term IPAM i.e IP Address management. Theoretically I got the definition from Wikipedia, but couldn't understand its actual need. Since for that we have DHCP then What is the need ...
7
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1answer
1k views

Will hosts do IP Fragmentation?

I heard routers alone do fragmentation. When a host is connected to the network with ethernet cable, how does it keep the MTU size as 1500? Will the host itself fragment and send only 1500 byte ...
4
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5answers
41k views

Finding the network and host address, and maximum number of host addresses

A subnet of an IP network has a range of IP host address from 172.19.40.1 to 172.19.47.254. What is the maximum number of host addresses that can exist on this subnetwork? I'm googling but not ...
4
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2answers
406 views

Mapping IP prefix to Organization

How would I go about mapping a prefix to an organization? I know I can use whois to map a given IP address to its AS and organization, but what about a prefix (as in, IP and some netmask)? Lets say ...
4
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4answers
2k views

CPU Impact of “debug ip packet” on Cisco Switches

in terms of CPU consumption and possible traffic disruption, what should I generally expect when I run the command: Switch#debug ip packet on a Cisco device in a large ISP network? Cisco devices in ...
118
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6answers
706k views

How do you calculate the prefix, network, subnet, and host numbers?

Example: IP: 128.42.5.4 In binary: 10000000 00101010 00000101 00000100 Subnet: 255.255.248.0 How could you determine the prefix, network, subnet, and host numbers?
5
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1answer
863 views

Remote Port Forwarding Cisco

I have a Cisco3900 called router A (192.168.100.1), which is interconnected to another router B (192.168.100.2). I want to access my server C 220.221.x.x (which is on internet). Router A (192.168.100....
2
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1answer
643 views

Do routers validate the IP packet length?

Do routers verify the actual IP packet size with that mentioned in the packet?
1
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1answer
754 views

Cisco Prime Infrastructure 2.0 : IP Type - Not Detected

I have a Cisco Prime Infrastructure server which has fully discovered all my devices on my network. But when I go to the "Clients & Users" tab (the new name of the old "User Tracking" feature), a ...
9
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2answers
59k views

Maximum IPv4 header size

I know the IP header length is a minimum of 20 bytes and a maximum of 60 bytes. But why? Why is the IP header length limited to 60 bytes? Is there anybody here that can explain it to me? Thank you.
1
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1answer
3k views

What is this UDP 5002 broadcast?

I hope this is an appropriate place to ask this. I'm confused because it's a broadcast at Layer 2 but it's UDP inside a VLAN with a destination to a unicast address (Y.Y.Y.Y). I was just wondering ...
5
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1answer
2k views

VRRP-Extended - can't ping

I have 2 brocade switches running vrrp-extended for a specific vlan. Connected to these 2 is an access switch with the default route set to the vrrp-extended virtual ip address. The problem is that ...
2
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1answer
376 views

Internet Protocol. Source Routing. RFC 791. Are the addresses in the Source Routing option 1-indexed?

I was reading pages 18-21 in RFC 791 about the Internet Protocol and in the sections on Loose Source and Record Route (LSRR), and Strict Source and Record Route (SSRR), and Record Route (RR) it says ...
5
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1answer
513 views

NAT translation mystery

We have an mail server and its private address is translated to public on a Cisco router. We've mapped it one-to-one using this command: ip nat inside source static 192.168.7.7 198.51.100.7 route-map ...
2
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3answers
5k views

Reliablity vs unreliable service at IP and Link Layer

I am taking about the 5 layer model. It is well documented that TCP is a reliable service and IP is best-effort delivery and hence unreliable (ref RFC 792 - TCP). Also, the data link layer is '...
8
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1answer
773 views

will ping work if there are 500 routers between pc1 and pc2?

As the ttl is 255 maximum for ipv4 on cisco routers, will ping work if there are 500 routers between pc1 and pc2?
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4answers
69k views

Confusing A, B, C network classes

I'm studying IPv4 addresses and came across this whole thing about classful addressing. I get the idea behind it, bit there is something I find confusing: There are two "ABC" ranges: First one: A: ...
8
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2answers
3k views

How is the IP prefix passed to the router?

First some background information on what I already know: An IPv4 address is a 32 bit address that identifies a node in a network. An IP address will have an IP prefix which determines the "Network" ...
5
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2answers
204 views

Locating a single IPv6 or IPv4 routable prefix at multiple data centers

Academic question (at the moment): Is it possible to advertise BGP routes to a given prefix (IPv6 and/or IPv4) from multiple different physical data centers? I guess this is multi-homing, but ...
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2answers
6k views

Why is the target IP address always my default gateway?

I am currently researching ARP packets using Wireshark and have found that when I ping a new computer asking for the MAC address that corresponds with the known IP address, my target IP address in my ...
1
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1answer
370 views

Basic question about private IP addressing -Class B

Below I will translate from decimal to binary just for the second octet The theory says the IP range is: 172.16.0.0/12 with addresses ranging between 172.16.0.0-172.31.255.2555 that translates to: ...
7
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3answers
5k views

How HTTP is converted to TCP and then how TCP converted to IP?

I know that in Internet Protocol Stack there are actually three layer. They are Application, Internet and Transport. Let's say HTTP in Application layer will be converted to TCP in Transport layer and ...
4
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3answers
2k views

Is there any recommended range for ip router id

Generally a router id will be set to highest loopback address if present or the highest ip address of physical interface. But most vendors provide a way to configure a specific value example:- " ip ...