Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange
Join us in building a kind, collaborative learning community via our updated Code of Conduct.

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

0
votes
0answers
8 views

“Unknown” identifier in OID for IP SLA

When I am doing a SNMP walk on the OID bellow. I get the correct IP SLA configuration, but I will get a set of random digits trailing which can be seen in the row bellow. What is the meaning of ...
0
votes
0answers
17 views

Can a webpage affect another device on the same network? [on hold]

The following just happened to me: While i was browsing a site on my pc i used my phone to google for something. Instead of showing the search results i was redirected to the same page that was open ...
0
votes
0answers
15 views

Modify IP header received from tun device and hand it over to a real net interface to send it to the remote host [on hold]

The question is as the title describes, what I am trying to do is: create a tun device, read the IP packet from the device; change the dst_addr, dst_port, src_addr, src_port and the port in its ...
0
votes
0answers
19 views

Errors in my VLSM addressing scheme attempt? [on hold]

I'm practicing addressing schemes using VLSM for my exam. The question and my answers are below. -I wasn't too sure about the number of hosts for the R1-R2 and the R2-R3 links. Are they correct?
0
votes
1answer
24 views

Setting Static IP for computers under a Switch [on hold]

i have a fixed Line, to which The router is connected (DHCP Enabled) Dynamic IP. I have a Switch connected to the Router. (8 Port TP Link) I have four machines connected to the switch and the count ...
0
votes
2answers
72 views

How does WAN work?

I understand the basics. WAN is a network that connects multiple LANs together. Usually the router is the connection between the LAN and WAN. But I have some questions books and the internet could not ...
2
votes
2answers
72 views

If the IPv6 address will be strictly based on EUI-64 logic then is there any real need of Neighbour Discovery Protocol?

I am building my fundamentals on IPv6 and have realised the multicast group is nothing but FF02::1:FFXX:XXXX. Here xxx is nothing but 24-bits of Mac-address (48 bits) with simple 7th bit magic. ...
0
votes
2answers
41 views

Why router interface need IP addresses while IP is constant during the journey?

A beginner question, I've recently read in Cisco CCNA R&S 200-125 official cert guide that the packet leaves the PC with a destination IP of PC2 (the target) but with the MAC of PC2 in case of PC2 ...
0
votes
3answers
51 views

Do OSI and TCP/IP models use the same protocols?

OSI is known for using hundreds of protocols to do its job. Both OSI and TCP/IP have Transport and Network(Internet) layers where TCP and IP protocols work respectively. It is clear that TCP/IP model ...
0
votes
1answer
50 views

What Are the Advantages of Static IP Addresses?

As there are two types of IP addresses, why static addresses are harder to maintain, and if they are so what is their advantage to have one instead of dynamic IP adresses?
1
vote
1answer
65 views

What are the key advantages and disadvantages of NDP compared to ARP?

So why they didn't use ARP in IPv6? is there any real benefit of doing this? what are the key advantages and disadvantages of using NDP instead of ARP? (In overall network performance, Security and ...
3
votes
1answer
63 views

Internet Protocol version 4 (IPv4) padding?

Where is ip padding insert in ip data-gram format, after payload?
0
votes
1answer
36 views

CRC done by ICMP?

cyclic redundancy check (CRC) done by Internet Control Message Protocol(ICMP)? how can help Time to live(TTL) for this?
0
votes
1answer
14 views

IP packets get queued in intermediate routers and can delay their delivery to the destination?

TCP segment go inside IP packets,there are many problems IP packets get queued in intermediate routers and can delay their delivery to the destination?
0
votes
1answer
21 views

IP packets can get dropped with TCP payloads?

TCP segment encapsulate it IP payload,if some way ip packet is lost in transmission. some time IP packet will be fragmented, i ask if this one fragment part will be lost in transmission.how can fix ...
1
vote
1answer
32 views

subneting question [closed]

i have doubt on this question, please clarify You are designing a subnet mask for the 172.16.0.0 network. You want 80 subnets with up to 300 hosts on each subnet. Which subnet mask should you use?
4
votes
1answer
161 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?
1
vote
1answer
39 views

What does 22/23 and 10.3/11.4 mean and why cannot access internet?

What does this specification mean? I asked the one who gave me this but I did not understand. Vlan 22/23 192.168.10.3/11.4 a) Does 22/23 mean that 23 subnets have been allocated b) The forward ...
2
votes
1answer
56 views

Packet vs Circuit switching

I have a 1Mb/s link each user uses 100Kb/s when active. With 10 user active 10% of the time, I can have 10 users in a circuit switched environment. Packet switching with 35 users, probability > 10 ...
17
votes
1answer
3k views

What is the practical use of a /31 CIDR or 255.255.255.254?

With a /31 subnet, we are left with zero usable hosts. The /31 subnet only has two hosts - one for network and another for broadcast. I am wondering why would someone ever use this subnet.
2
votes
1answer
49 views

End-to-End delay

I’m working through questions from computer networking top down approach and was hoping to get some clarity on the end-to-end delay calculation. At this stage we are not considering processing, ...
1
vote
2answers
64 views

Why to use public IP addresses within private networks?

I have started to work in a multinational company which has a global network spanning across 4 continents (20 0000+ network devices). I noticed that a lot of end user devices (PCs, laptops) have IP ...
0
votes
0answers
7 views

How to find subnet mask using First and last usable IP address [duplicate]

The first and the last IP addresses of a subnet are 192.192.8.0 and 192.192.63.255 respectively. how to find the subnet mask?
2
votes
1answer
312 views

Can a 172.168.10.0/28 be a class B Subnet

I am starting my studies in networking and starting off with the basics of IP addressing and Subnetting with CIDR values. My Question here is 1st how can you tell the subnet class of an IP address ...
1
vote
1answer
41 views

Ip aliasing on cisco router

We have a D-Link router (DSL-2730R) with the "Alias Ip Address" feature. This enable a logical network from the primary IP. I want to do the same on the Router Cisco Rv-110w, ¿it's possible, what ...
10
votes
2answers
3k views

Is the MTU of Ethernet still 1500 Bytes?

So basically do the modern routers in the internet still use 1500 as the MTU of Ethernet? or the 1500 Byte was for the old days? What I'm asking here is what is the MTU of Ethernet in modern Networks?...
0
votes
1answer
49 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 ...
0
votes
1answer
18 views

Implications of ipv6 on LAN security [duplicate]

I'm not sure whether this is really the correct place to post this question, because it's not really about a "professional" setting. However, I have the standard setup with computers behind a netgear ...
2
votes
2answers
46 views

Bad mask for Cisco simulator GNS3

I am using the GNS3 simulator, and I need to connect two Cisco C7200 routers. When I enter the ip address 126.0.0.4 255.255.255.252 command, I get Bad mask /30 for address 126.0.0.4.
4
votes
1answer
106 views

IPv6 - ULAs - Am I understanding use correctly?

Tinkering more with IPv6 and trying to unlearn the IPv4 stuff. Assume my router is correctly respecting the reserved addresses. LLIPs aren't going to pass through to the router's outside interface ...
0
votes
1answer
28 views

Does anyone know why certain TCP inner workings are called FLAGS? [closed]

What's the reason for calling certain TCP inner workings flags?
0
votes
1answer
24 views

Discovering public ip from wifi signals, shodan, parent router NAT [closed]

MAC addresses innately do not change right? and you're able to scan for broadcasting APs where you'll be able to detect different nearby mac addresses of each AP.. Public IP addresses change, ...
0
votes
1answer
30 views

How to add new tasks to layers of OSI or TCP/IP?

Which software and hardware parts of a computer are responsible for adding or removing values to the initial payload of a data packet in every layer of OSI or TCP/IP model? In other words, which parts ...
2
votes
1answer
60 views

Why does software mention TCP or TCP/IP when it means just IP?

When I configure a network interface in Windows to have a static address, I have to go to TCP/IP settings. In this TCP/IP settings dialog I can set IP, subnet and gateway, which are IP- and route-...
0
votes
1answer
35 views

Routers and RIP violation of isolation?

I'm studying networking from the book 'A top down approach' from Kurose and Ross. In the book it is stated that routers are generally considered Layer 3 devices (i.e. implementing the stack up to ...
0
votes
1answer
68 views

How do ICMP packets travel in a networks?

Questions: I'd like to know how ICMP packets travel in a network? Are they encapsulated within IP datagram? The RFC 792 doesn't explicitly states the layer of ICMP. Are ICMP messages sent using a ...
0
votes
1answer
18 views

Sys Routing Table Router: Destination IP, Gateway IP and Public IP are different, something unusual? [closed]

I am currently studying my home network router Sys Routing Table and attempting to resolve WHY my Public IP (assigned by my ISP), Gateway IP (WAN) and Destination Network (WAN) are all different. I ...
-6
votes
4answers
92 views

What is the difference between DHCP and NAT?

Both seem the same to me. I don't see how DHCP is different from Dynamic NAT. Can anyone please help?
2
votes
2answers
67 views

How does/did an ISP serve so many people over IPv4

Whilst reading Tanenbaum - Computer Networks they talk about IP scarcity at the level of ISPs: IP addresses are scarce. An ISP might have a /16 address, giving it 65,534 usable host numbers. If it ...
6
votes
1answer
73 views

Why is an IPv6 Link-Local Address a /10?

I'm currently studying for my CompTIA Network+ Exam and am a bit confused as to why the IPv6 link-local address is a /10 and not a /12 or /16. Since each character in an IPv6 address is 4-bits and ...
8
votes
3answers
1k views

How do VPN's forward network traffic? (Layer 3)

I am looking for some info on how VPN's (Virtual Private Network) forward network traffic through its VPS (Virtual Private Server). Take an example where you are connected to a VPN. You make a ...
1
vote
1answer
27 views

What is a subdomain (in relation to IP)? [closed]

My understanding is that when you buy a domain, you buy the right to associate that domain name with ANY IP address you want. So, if I buy "example.com", I can say that when someone looks up "example....
3
votes
1answer
77 views

Can a host behind a basic NAT visit two services on a server at the same time?

When reading Data Communications and Network (5th edition) by Behrouz A. Forouzan, I have trouble with the explanation for NAT. On page 546, the book describes a modifying-IP-only NAT (a.k.a. basic ...
0
votes
1answer
41 views

IP/Device Question

I am very new to this field and I want to ask a quick question about IP/Device HTTPS. When we type in the IP address of the device (cisco switch, router, firewall, etc), we can access to the web ...
2
votes
2answers
51 views

Before the invention of Classless Inter-Domain Routing (CIDR) did hosts have subnet masks assigned?

Before the invention of CIDR, did hosts also have a subnet mask assigned or only have an IP address and the network was determined by the class of the IP address?
0
votes
1answer
67 views

GNS3 IP helper in Multiple Vlans

Good day everyone, I'am having trouble getting VPCs from VLAN 3 to communicate with the DHCP on Vlan 3 I've also tried configured IP helper on the Router but to no avail. Router Configuration dump ...
0
votes
0answers
39 views

Net-flow Data with Destination 0.0.0.0

I have been using a combination of flow-cat, flow-filter, and flow-stat to sum the number of bytes to each destination from a specific source IP address. The command I run looks like this: zcat flow*...
0
votes
1answer
65 views

IP Networks Issue

I've been facing this issue for quite a long time now, and couldn't figure out its logic. So let me explain what I have: I have Xampp installed on a Linux Desktop PC which is connected to two local ...
1
vote
1answer
46 views

How do protocols like PPTP, L2TP work below IP level

I have been using these protocols without deep understand how everything works under the hood. I understand a process of tunneling as follows When we are using protocols like OpenVPN, IPSec, SSH ...
0
votes
1answer
67 views

Why am I getting different public ip from two computers on the same local network [closed]

This is a network setup in a lab of academic institution PC1: Connected to wired LAN socket of Lab. Connection is DHCP. IP: 10.21.106.221 Netmask: 255.255.252.0 Default Route: 10.21.107.254 ...