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Transmission Control Protocol/Internet Protocol (TCP/IP) is the set of networking protocols that define end-to-end connectivity specifying how data should be packeted, addressed, transmitted, routed and received at the destination. This functionality is organized into four abstraction layers which are used to sort all related protocols according to the scope of networking involved.

I subscribe to a site similar to this one that answers a wide scope of questions. The site is www.justanswer.com  My internet speed averages 950 Mbps up and down via fiber. I have a late model router and my problem occurs no matter which computer I am using. Frequently it will give me the errors as pictured in the included photos. It is the ONLY site that I have this difficulty with. The "Customer Service Representatives" indicate that they are having no problem. This has been ongoing for over two years. Can any expert shed some light on this difficulty? I use Windows 10 and McAfee Total Protection. If it is something you think I am causing I am sure you will tell me how to remedy the problem. If you think it is the site in question please give me a short and to the point description for them so that their techs can address the issue with the details that you think are important. Thanks Experts!!Result one of two when attempting site accessResult two of two when attempting site access
I am in process of setting up a new Windows 2016 server for a client. This is my first W2016, Prior to this, I only dealt with W2008 and W2011 SBS. I've setup an internal static IPv4 address, and a fake static IPv6 entry based on a recommendation to stop EventID 10020 entries in the logs.

When I pinged the server by the host name, I get a response from the IPv6. When I use ping -4 host, I get the normal IPv4 response (see first screenshot attached). Based on a few articles that I found, It turned out that that the default priority in Windows 2012 and newer is to have IPv6 preferred priority over IPv4.

So, I decided to change the priority to IPv4 over IPv6. I followed the instructions in the two article linked below. The second link is very descriptive on this topic. After running the appropriate commands, you can see in the second screenshot below that I was able to change the priority, and that the regular ping (without the -4) was able to return the IPv4 values


I rebooted the server, and sure enough, I was back to square one, with getting the IPv6 reply to a regular ping. I did some more research, and came across the link below from Microsoft https://support.microsoft.com/en-us/help/929852/guidance-for-configuring-ipv6-in-windows-for-advanced-users

I downloaded their fixlet for "Prefer IPv4 over IPv6 in prefix policies", and …
What is the Windows Network Adapter IP address? How does this work?
Dial-up Network Adapter IP addressIs this a subnet address, with an implied mask based on the first number?

i.e. if the first number is in the range 0-127, then the mask is and the remaining 3 numbers are ignored?
So in this example the first number is 94, so any TCP/IP traffic with a destination address starting with 94 would be directed to this adapter?

And if the first number is in the range 128-191, then the mask is the remaining 2 numbers are ignored?
If the Network Adapter IP address was, any message with destination IP address starting with 132.99 would be directed to this adapter?

Likewise, first number 192-223, mask is, last number is ignored?
If the Network Adapter IP address was, any message with destination IP address starting with 199.10.9 would be directed to this adapter?

Am I understanding this Network Adapter IP address correctly?
2001 in IPV6

I have seen several examples in IPV6 and most of them starts with 2001.. I am not sure what it means that number.

Any explanation ?

Thank you
understanding RIP timers

I have run into the following terminology in RIP. I would like an Expert to explain the meaning of each:

Thank you

Sending Updates every 30 seconds
Invalid after 180 Seconds
Hold down 180 seconds
flushed after 240 seconds
BGP Regular Expression

Can someone explain the difference between the 2 regular expressions below:

Assuming our AS is 5555

show ip bgp regexp ^3257$
show ip bgp regexp _3257$

I believe this : ^3257$  will show the  AS directly connected to our AS
 _3257$  : this will show all ASes that precede AS 3257 including the AS 3257

Any Comment is welcomed

Thank you

I want to see ports 9002-9021 open on this server.

i checked on firewall all traffic is allowed

but when i ran netstat -a i see these ports not listening.

how do i install listener on this server
I have a device which communicates with the computer over a serial port. It communicates using PPP over TCP/IP.

To get from the serial COM port to the network, we create a modem of type "communicate directly between two computers" associated with the COM port. Then we create a network adapter associated with the modem. Then we are able to communicate with the device using its IP address. (IPv4)

Now i want to intercept the PPP frames somewhere along this path, modify the To/From IP address, and reinject the packet somehow. Do this for traffic in both directions.

I can write a user program that opens the serial port and performs I/O with the port. I can read and parse PPP frames coming from the device, extract the IP datagram, modify the IP address, calculate a new checksum, and then... Then I'm not sure how to inject the modified frame back towards the network.

I'm also unsure how to intercept PPP frames headed in the other direction, going to the device.

I've been looking into writing device drivers. (I wrote a device driver eons ago for a VMS computer.) Not sure what device driver to write. I see callout drivers, filter drivers, maybe create another virtual COM port I can inject the stream back into.

I need a deeper understanding of how these device drivers get connected together and pass data back and forth. How does a modem device driver communicate with a COM serial port driver and a network adapter driver?

Maybe the serial port isn't the best …
I have 2 embedded systems which I want to FTP a file to using a laptop running Windows 10. The problem is each embedded system has the same hardcoded IP address.

When we talked with just one embedded system this was no problem. The setup looked like this:
Original Setup With One Embedded System
Now we want to talk to two Embedded systems (and eventually more). Since each system has the same identical hardcoded IP address, this poses an IP address conflict problem:
IP Address Conflict
A solution I've considered would be to somehow insert some Network Address Translation (NAT) to translate the identical IP addresses to unique IP addresses. One way would be to have two Network Stacks, each one handling the bytes coming from a Virtual Port:
Two Network StacksThis is a rather heavy handed solution. Each Network Stack has a lot of work to do, interpreting bytes as TCP packets, handling the TCP packets and protocol, sending appropriate ACK messages, etc. There are some open source solutions I've browsed.

Windows already has a stack as part of its OS. It would be nice if I could shift that part of the burden to the OS and just keep the Network Address Translation (NAT) part somehow.
NAT onlyThe NAT would need to assemble TCP packets from the stream of bytes from the Virtual COM Port, perform the IP address change (calculating a new checksum), then somehow forward that new TCP packet to the network.

Is there open source code for parsing a stream of bytes into …
Calculating the Subnets.

I am using the online Subnet Calculator.  Some Data displayed on the calculator and indicated by the Red arrows on the screenshot below  need some explanation:

how did they come with subnet bits: 12
Maximum subnets 4096
host per subnets :14
subnet ID :
Broadcast address :

Thank you


Is it possible to use Oracle db as a TCP IP server , so it can accept incoming TCP IP requests ?
I'm familiar with UTL_TCP but this seems to be working only as a client and other servers can't connect to it ...
EDUCATIONAL QUESTION: I need to gain some knowledge our of necessity. Here is the situation. I do NOT know my way around things such as: 1. What the function of DHCP is; 2. Why port forwarding is necessary in some instances; 3. How to configure the ip addresses of my surveillance cameras; 4. How to start anew with my NVR and surveillance system.

I did not want to take the time to educate myself on these items since I would seldom have need for this knowledge. However, since I just got a new fiber isp and virtually nothing operates properly on the surveillance system I think that I must gain the knowledge necessary to do this myself. The company I purchased 70% of the system from will assist me somewhat but refuses to assist in any way at all for the cameras that I did not purchase from them. There are many free utility programs available that I have  installed, however I need the knowledge to determine what to do with them. I think you get the picture. What my question is: Can any Expert advise me of an online course that will teach me what I need to know to understand this area of technology that will not take me overboard? I will not be doing this for a living. I just need to know what is needed to enable me to restore my system to default and start anew and KNOW what I am doing. I wish I didn't have to take the time needed to learn this, but I cannot locate a person that can guide me through all that is necessary to get things up and operating again. I would feel …
Meaning of TTL in PING Reply

I have pingged 2 devices that have the same number of Hops away.
One shows TTL:124
the other shows TTL:250

I wonder how is the TTL calculated in this case .

Thank you
Host Address Range in IP Subnetting

I have this IP address: subnet mask

how can I calculate The host address range to come up with first host:  and the last host:

Thank you
I am having trouble using the Mitov Openwire VCL components TVLIPCamera.
I am writing a Windows 32 C++ application using Embarcadero XE10.2 to stream video from an IP camera.
I have a single for Form1 with a TVLIPCamera and VLImageDisplay component, the output pin of the TVLIPCamera component is connected to theinput pin of the
VLImageDisplay. I have set the URL property of the camera component to http://username:password@
the code compiles and runs but there is no video displayed. Mitov advertises the TVLIPCamera component as suitable for use with a "generic IP" camera although the term "generic" is not defined.

I can test the camera with an web browser using the following URL Which then prompts me for a user name and password,
after entering both, live streaming of video from the camera is displayed in the browser.
 I have monitored the network traffic to the camera with Wireshark and when the RAD C++ builder application runs, a TCP connection is made with the camera and Wireshark shows 9 TCP packet exchanges but then communication stops.
Any suggestions as to what the URL should be or otherwise what the problem might be would be greatly appreciated ?

The IP camera is a SANNCE Security Cameras Wifi 1080P which is manufactured by ANNKE
Hi Experts.

Got a question we seem to disagree on amongst colleagues.

In "modern" Windows environment (2008, 2012, 2016) with multiple DNS servers within unique AD (let's keep it simple for argument sake and not talk multi AD or forests), what is the best practice when it comes to IP assigning.

#1. Each DNS server has itself (loopback) as unique DNS entry in the TCP/IP settings, and any second DNS is declared in the Name Servers tab.
#2. Each DNS server has itself (loopback) as Primary DNS entry AND any second DNS is declared as Secondary DNS entry in the TCP/IP settings.
#3. Each DNS server has the secondary DNS declared as Primary AND itself (loopback) in the TCP/IP settings.

All three scenarios seem to work 99% of the time, when it comes to AD replication mostly, but at times, we like to point fingers at each others config for any downtime that occurred, and subsequently buy a round of coffees for the team :)

Any Experts wish to comment ?
What is the purpose of in-addr.arpa within Server 2016 DNS?

Within Server 2016 DNS Manager what are SRV records used for?

SRV records
Within DNS manager, what are the values in the brackets "[ ]" within the Data column?

Data values
We just switched to a different ISP provider a few days ago. Since then, there have been several Bad Address entries in the DHCP server (Windows server 2012). After deleting them, they'll appear again in an hour. Their Mac addresses are not shown in the address lease.

I used the DHCPFind to check if there's any other DHCP server on the network. The result is attached.

How do I find out what device(s) is causing the issue? Or How to fix this issue?
Dear EE,

I have found warning at DB server when user has reported Application dis-connectivity.
1)  User reported Application Dis-connectivity Error as attached.
SQL Error

2) We investigate the issue and look in to the Event logs and found below WARNING. Event Id : 4227

TCP/IP failed to establish an outgoing connection because the selected local endpoint was recently used to connect to the same remote endpoint. This error typically occurs when outgoing connections are opened and closed at a high rate, causing all available local ports to be used and forcing TCP/IP to reuse a local port for an outgoing connection. To minimize the risk of data corruption, the TCP/IP standard requires a minimum time period to elapse between successive connections from a given local endpoint to a given remote endpoint.

Please confirm will user application error is due to this above error.

Hi!  anyone have any luck with a "TELNET" like connection with MS ACCESS?    I send simple text commands to a connected unit via TELNET.    By TELNET I mean using a communications application that converses with a connected device via IP address.     Something like sending "readbuffer01" and a response like "0,00.4,2" is returned by the conneted device.   I do this over a TELNET application like Tera Term set up for IP of the connected device xxx.xxx.xxx.xxx format for IP and TCP/IP port 3602 emulating a VT100 terminal.   Any way that ACCESS can send commands and listen for a response like these terminal programs.   I am basically trying to automate data collection over the tcp/ip connection and store in a form/table.

Hi Experts,
How to grep connected tcp IP & Port connection then forcefully kill using batch.

netstat -a output is

Active Connections

  Proto    Local Address                        Foreign Address                State
  TCP            ESTABLISHED
  TCP            ESTABLISHED
  TCP            ESTABLISHED
  TCP                   ESTABLISHED

Need to forcefully kill all TCP connection which is connected with
I bring my (Windows 10 Pro) laptop around to do support in a few different networks - some with DHCP and some where a fixed IP-address is needed. Have tried to find a way to make shortcuts to set the fixed addresses (or set the network adapter back to dhcp), but haven't found a way to do it. Thinking of commands in a batch-file. Any suggestions?







Transmission Control Protocol/Internet Protocol (TCP/IP) is the set of networking protocols that define end-to-end connectivity specifying how data should be packeted, addressed, transmitted, routed and received at the destination. This functionality is organized into four abstraction layers which are used to sort all related protocols according to the scope of networking involved.