Last call to make your voice heard! Our 2022 Developer Survey closes in less than a week. Take survey.

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.

Filter by
Sorted by
Tagged with
2 votes
2 answers
56 views

Loops in routers-same packet?

Considering a loop topology between a few routers with a host connected to one of them, when it's default routing directs to the cycle. Even when observing Wireshark, how can we know its the same ...
0 votes
0 answers
14 views

Formatting of segments destined for the same destination TCP as discussed in the Cerf & Kahn's Paper [closed]

In the Cerf & Kahn's Paper - Cerf, V.; Kahn, R. (1974). "A Protocol for Packet Network Intercommunication" (PDF). IEEE Transactions on Communications. 22 (5): 637–648. - they discussed ...
1 vote
2 answers
70 views

What should we do if the number of bytes to be transferred are not in multiples of eight in ipv4? [duplicate]

(it is take from book called special edition tcp ip, pic taken for better formatting and ease to read) Theory that I am trying to understand-: So i found a question that is relevant to this-: ->a ...
0 votes
1 answer
21 views

Constraint on length of message & segment to be integral number of bytes, as mentioned in Cerf & Kahn's Paper

I have a question about the below excerpt from Cerf, V.; Kahn, R. (1974). "A Protocol for Packet Network Intercommunication". IEEE Transactions on Communications. 22 (5): 637–648. ... ...
24 votes
7 answers
9k views

Does CIDR really "do away" with IP address classes?

I am still struggling to understand to what extent CIDR really renders IP address classes obsolete. Here's what I understood so far: It's ridiculously inefficient (and impossible, too) to assign ...
0 votes
0 answers
15 views

How many /56's are there in a /49 IPv6 [duplicate]

I am studying subnetting in IPv6. I came across the following question from a website called Subnetting Practice, which I will quote below. How many /56s are there in a /49? Could someone please ...
0 votes
2 answers
35 views

Simple IPv6 Global Unicast question

I was reading this article which states: RFC 3587 states that out of the 128 bits in IPv6 addresses, left most three bits are must be fixed as 001. Remaining 45 bits are reserved for global routing ...
1 vote
1 answer
28 views

How is 65535 bytes is total length of IP datagram?

The maximum size of an IPv4 packet is 65,535 because the Total Length field is a 16-bit unsigned integer, which has a possible 65,536 values (from 0 to 65,535). This created 2 confusions for me. Say ...
0 votes
2 answers
26 views

How to use IP pool

I am just beginner, I just want to setup my mini data center and for testing i get a FTTH connection and /30 ip pool, ISP reply is something like that, "IP Pool 103.15.xx.xx/30 has been assigned ...
0 votes
1 answer
17 views

What are the IP/MAC addresses of requests between 2 different subnets? [closed]

Assume that networks 172.15.10.0/24 and 172.15.11.0/24 are connected through a router with interfaces 172.15.10.254 (MAC3) and 172.15.11.253 (MAC4). If host A sends a packet through its network ...
8 votes
1 answer
1k views

What does it mean to “plumb” an IP address?

Plumbing an IP address means what? What are some examples of it?
1 vote
2 answers
86 views

Why shortened version of IP4 exists and it is undocumented but supported everywhere?

For example there is an IP address 192.168.0.1 It is clear that you can use it as the full line, but try that one 192.168.1 It will also work, and it will be automatically converted to 192.168.0.1 ...
0 votes
1 answer
15 views

DHCP Discover Broadcast and its IP (255.255.255) [duplicate]

Cheers, I am trying to learn more about DHCP, and when studying about the session that DHCP goes through every one mentions that it broadcasts a discover message at IP: (255.255.255.255) (as seen here ...
2 votes
3 answers
6k views

What is the relationship between the IP address and MAC address?

I own a MAC address and I want to know from it, the IP address.
0 votes
2 answers
99 views

Why in the TCP/IP model the link & physical are one?

I'm currently learning about the OSI model and the TCP/IP models, and I was wondering: Why in the TCP/IP model the physical layer and the data link layer are combined? I'll state how I understand the ...
0 votes
3 answers
5k views

Why there is only one hop in the tracert?

I use the tracert to a remote server IP address: C:\Users\lll>tracert 103.224.19.11 Track by up to 30 hops The route to f1.FF-SALE.COM [103.224.19.11]:    1 44 ms 44 ms 44 ms f1.FF-SALE.COM [103....
0 votes
1 answer
61 views

Why is this 254.63.0.1, not a valid host address?

Getting the below error, when trying to configure the ip address 254.63.0.1 as an SVI. Switch(config)#interface vlan 254 Switch(config-if)#ip address 254.63.0.1 255.255.0.0 Not a valid host address -...
1 vote
3 answers
61 views

Why the host part of a Mask is 254 (256-2) instead of 253?

Don't hate me for being such a newbie but I'm so confused. If we have 32 bits, each octet adds up to 255, why the host part is 254 (in a 255.255.255.0 mask) instead of 255 - 2 ? Thanks so much for ...
0 votes
0 answers
7 views

How IP packet's payload bigger than the whole former PDU (segment)? [duplicate]

As far as I know: File is too big ---> Fourth layer (TCP or UDP) divide it to a multiple segments ---> Then each segment encapsulated separately into a packet. What means if I have 10 segments, ...
1 vote
1 answer
33 views

How does a computer determine that an Ethernet frame contains an IP packet? [duplicate]

So far as I can tell, there is no "Next Protocol" ID at the Ethernet / data link layer. Nor do IP packets seem to contain any magic numbers for identification purposes. Does the OS bind each ...
0 votes
2 answers
102 views

Inherent flaw in stateless firewalls?

I am but a lowly (software) developer dabbling with setting up a network in AWS and am having trouble understanding the fundamentals of stateless firewalls, or Network ACLs as they're also referred to ...
2 votes
1 answer
62 views

Custom option in IP header

I would like to add (or piggyback on an existing not used) a custom option to the IP header. I've full control of the IP stack at both end points, but I've no control on all the hops in the route (...
0 votes
0 answers
7 views

Dividing network into subnets [duplicate]

My teacher uploaded this example question and solution as explanation of the topic: I watched some videos about it but none of them made it fully clear, what I don't understand here is: What are ...
3 votes
1 answer
51 views

How are IP broadcasts handled at lower levels

When I use a broadcast IP address, for example 198.255.255.255, what will happen when it gets passed down to the link-layer which will then look for the corresponding MAC address in your ARP table. ...
0 votes
1 answer
1k views

How to Run Static IP Through Comcast Business Class Modem to Router?

I apologize in advance for this kind of nebulous question, but I'm very stuck after many hours of trying and I need help. Here's what I have: Newest model of the Comcast Business Class Modem/Router ...
5 votes
4 answers
12k 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 ...
0 votes
3 answers
47 views

why ip adresses are divided into network portion and host portion when we already have NAT [duplicate]

I don't understand why ip adresses are divided into network portion and host portion? is the host portion really necessary when we already have NAT? for example, if ip addresses only have network ...
3 votes
2 answers
283 views

Why can IPv4 and IPv6 use strict source routing(in options field) and flow label respectively inspite of connectionless protocol?

In IPv4 option field one field option is source routing option this means packet will always be routed by router Or not. Packet can also be routed by source such routing is known as source routing. ...
8 votes
3 answers
7k views

Usage of Flow label in IPv6 header?

I have been reading the IPv6 Flow Label Specification (RFC 6437) and I would like to ask about the purpose of setting this label. In case of just using the 2-tuple (source address, destination address)...
129 votes
6 answers
801k 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?
1 vote
1 answer
110 views

How does Network Layer behave when client received a unicast DHCP offer?

I went through various stack exchange post to understand the concept of DHCP offer when it comes as a unicast to client from the DHCP server. A server can send a unicast DHCP offer since it knows the ...
7 votes
7 answers
3k views

Why is classful addressing considered waste?

I am trying to understand the addressing strategies. But there is something which I can't grasp. Maybe I am missing a very basic point, if so, I am sorry beforehand. From my researches, let's say, if ...
0 votes
1 answer
40 views

point-to-point at IP layer

I was reading one of 5G standards specifying signalling transport https://www.etsi.org/deliver/etsi_ts/138400_138499/138472/15.06.00_60/ts_138472v150600p.pdf and noticed (section 6): The IP layer of ...
20 votes
3 answers
34k views

What is Link-local addressing?

I noticed that IPv4 reserved 169.254.0.0/16 and IPv6 reserved fe80::/10 for link-local addressing. While I saw IPv6 uses both fe80::/10 address and my private IPv6 address fd00::12 to communicate with ...
3 votes
1 answer
844 views

Filtering IP packets that contain IP options using ACL

Is it smart to have ACE #deny ip any any option any-options enabled as part of hardening the router? Is there some legitimate traffic that use IP options? Or should I use selective drop?
0 votes
2 answers
35 views

Is there any benefit of combining several unicast into a single multicast?

If a node has to send the same data to multiple nodes, it is obvious that multicasting the data would improve bandwidth usage. However, if a node has to send different data to different nodes, would ...
9 votes
6 answers
15k views

What is the purpose of subnetting, if we have NAT?

As I know, NAT is the system, that divides IP addresses into two categories - public and private. Public represents the local network from the outside and private represents the device from the inside....
1 vote
4 answers
1k views

Why does Nmap not detect a host which is active and responds to Ping?

I have connected to another laptop via the LAN cable, i am able to access the services running on the other laptop via Ip & Port. When i Ping that Ip, the machine is successfully responding. But ...
0 votes
0 answers
17 views

How does a host use its default gateway? [duplicate]

Each host has its own default gateway and uses that to send packets outside of its network. But in each packet, there is only 1 header field for the destination IP address. So, how can that host send ...
0 votes
2 answers
2k views

"Protocol Application Invalid" in CISCO IP PHONE 7940! [closed]

I have a boot issue in Cisco IP Phone "Protocol Application Invalid." So I want to update my firmware. I made my PC as TFTP and DHCP Server and connected my PC and IP phone in same vlan, but it is ...
0 votes
1 answer
50 views

Cisco Packet Tracer gives "Invalid IP Address" when I assign an address to a router [duplicate]

I was given an exercise where I have an IP address range and I have to configure multiple sub networks from that range. The address is 238.61.192.128 with the mask 255.255.255.128 (/25). I created my ...
4 votes
2 answers
6k views

What is the difference between MAC and İP broadcast addresses?

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

If current IP ranges for PCS are in conflict with a new systems network, how do you re-IP the PCs and the Servers?

I have a question about IP conflicts. Let's say you have a company building full of PCs on a network. Then a firm buys out that company and institutes its new system and new network for that building. ...
1 vote
1 answer
468 views

IPv4 to IPv6 one-to-one mapping for a whole Class A range

Are there any IPv6 technologies that support translating one-to-one mapping from IPv4 to IPv6 for the whole Class A range, like 10.0.0.0/8 network to a particular IPv6/40 range? Preferably for A10 AX ...
2 votes
3 answers
36k views

Why is 192.168.1.1 the most common default router gateway? [closed]

Why does most routers has default ip gateway 192.168.1.1? How do I change the gateway? If it gets changed, does every pc connected get a modified ip?
0 votes
1 answer
597 views

How to configure IP addresses in cisco packet tracer?

Hello I am working with Cisco packet tracer. I have two laptops connected to a wireless router with IP addresses assigned using DHCP. The router's Internet IP address is 10.1.0.0 and the LAN address ...
0 votes
1 answer
60 views

What does an IP Address with CIDR represent precisely?

This question is more a question of definition then a technical one: You have some network with the network identifier 172.16.0.8 and a subnet mask 255.255.255.248 (/29) We know that the usable ...
0 votes
3 answers
68 views

Routing traffic within the subnet - How to decide CIDR range?

I am following this tutorial to configure multiple subnets and firewall: https://networkfirewall.workshop.aws/setup/distributedmodel.html This tutorial shows how to filter traffic through the ...
3 votes
1 answer
80 views

Identify vrf within packet capture

I have a scenario where i am capturing data where mutiple customers vrfs traverse I am looking at my capture and ofcourse i see source & destination However, these addresses could come from ...
0 votes
1 answer
58 views

How does ISP know which port to open for incoming answer from a site requesting, since sites answer in different ports from ones we ask? [closed]

I wondering how does ISP open door for incoming answer from a requesting site since the answer doesn't come from the requesting door, and how to achieve my computer IP since it's behind ISP firewall, ...

1
2 3 4 5
19