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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.

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what are the things to check before IP change on windows server?
How to find what all application has IP hard coded? any tools to find what all application are dependent on old IP?
Change of reverse lookup ip on pointer record and host A record and static IP on server and anything else need to be change after changing static IP on server
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Hi.  We are recovering from Irma and I have noted a strange issue on a few networks where their internet went down.  The specific account I am concerned with is configured as following:
Netgear Router bridged to Comcast Modem - Router
2011 SBS Server - DNS, DHCP & AD - file sharing   IP

I have configured the workstations to use the following configurations:
LAN IP (each PC has it's own)


After setting this up on each PC, I still cannot connect to, nor ping the server or the other devices on the network.
They should be on a domain network, and they are definitely NOT home or Public at the least.

As this has happened on different networks, and the common link is they are Comcast and this has happened since we lost internet (it is popping in and out intermittently).  I just need to get the workstations to talk to the server.

Any ideas or insights?
Please explain the usage of the Multicast ip addresses below

I have seen different Multicast IP addresses used , the most common are shown below. Correct me if I am wrong : I believe this is used by the IGMP querier to  find out if there is any receiver interested in Multicast. : Probably this address is used by the IGMP querier for Auto-RP discovery (it is a little bit vague) : probably this address is used by the IGMP querier when it is configured to use PIM protocol (I am not sure if it is specific to PIM version 2 or any version) : is used by IGMP host (the Receiver) when it leaves the multicast group this is used by IGMP Version 3 receiver, But I am not sure if it is used when the receiver leaves the Multicast Group or it uses it in different circumstances . (please clarify)

Thank you

We use an RDP session through a VPN tunnel to connect to our hosted software out of state.

We constantly experience latency through all of our VPN tunnels.  I can run a constant ping from our hosted provider back to our environment to get a small picture how bad the response times of the pings are.

The ping times will be consistent for a little while hovering at 55ms - 67ms and then we will see "request timed out" multiple times and then ping times will rise.  It seems like the ping times fluctuate a lot  (I assume they would as the signal is traveling through multiple possible connections).

When ping times are at 55ms or less everything seems fine.  However, when it goes up from their end users report latency.

We are not hard lined to our ISP as everything is wireless.  Our internet pipe should be sufficient at all locations as we have spoken with our ISP and we do not hit the high water mark on our bandwidth - only rare spikes the main site.  

We are not hitting the high water mark on bandwidth usage at any of our other sites.  Is there a good piece of Enterprise level software that one could use to help get a clearer picture of where the issue occurs?

What kind of architectural questions should we be presenting to our ISP?   To our hosted provider?

1.  Is your VPN Server over-utilized?
I have a printer that is printing a huge job and many and I can not cancel it. I think someone has a tcp ip connection to it.  it could be any PC of hundreds.  
is there a piece of hardware I can attach to the drop to clear all the jobs.  I
How to enable Mysql server access through TCP/IP
where mysql installed in Centos machine.,.I am trying to access using mysql workbench it through TCP/IP but throwing error .. attached screenshot.
Where as when I select TCP/IP over SSH .. I can able to connect .
Here is a simple example of CIDR IP blocks

I would like to change them into

So from 4 IP blocks to change them into 1 IP block.

I know how to manually aggregate CIDR blocks, but I have over 5.000 IP blocks.

I’m looking for a tool that will automatically combine adjacent IP blocks into larger IP block.
I'm receiving this error among others, listed after. I have no idea why this error is coming up! how do I address?

Event 4879 MSDTC Client 2
MSDTC encountered an error (HR=0x80000171) while attempting to establish a secure connection with system SERVERNAME.

More errors that I don't understand and one that Microsoft doesn't even seem to know about (starting with that one)

The error that MS has no info on in Event ID Online help
Event 4230 TCP/IP has chosen to restrict the congestion window for several connections due to a network condition.  This could be related to a problem in the TCP global or supplemental configuration and will cause degraded throughput.
Need to refresh DHCP IP address reassign Needed to command
Let me start off by saying I'm in no way shape or form a network engineer. I am an IT Generalist and I'm in the process of trying to figure out why some remote IP phones have stopped working for a client. I don't want to get too into the weeds, but I've looked at and compared traffic from working equipment to this non working system. What I've seemed to have boiled it down to is:

Working: Phone tries to communicate on Port 6801 with server, server sends RST, ACK - phone then tries Port 6802 - same. Finally phone tries port 6800 and everything works fine.

Non-working: Phone tries to communicate on Port 6801, receives back a RST (without ACK). Phone continually tries to communicate on port 6801 until it reboots and starts over.

I've captured traffic at the server, at the firewall and at the phone. It seems like the packets are leaving the server as RST, ACK, leaving the Firewall as RST, ACK but arriving at the remote location as RST.

I'm looking for ideas on what could cause this?
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This webinar discusses:
-Common barriers companies experience when moving to the cloud
-How SD-WAN changes the way we look at networks
-Best practices customers should employ moving forward with cloud migration
-What happens behind the scenes of SteelConnect’s one-click button

I have an IPv6 box that is supposed to be routing via HE. I have radvd configured, so it hands out a /64 subnet as follows:

interface enp2s0
      AdvSendAdvert on;
      AdvManagedFlag off;
      AdvOtherConfigFlag off;
      prefix 2001:470:1f17:204::/64 {
            AdvOnLink on;
            AdvAutonomous on;
      # This is the DNS server on the internal interface
      RDNSS 2001:470:1f17:204:feaa:14ff:fe53:2eec {
      route ::/0 {

I have the interfaces up as follows: enp1s0 (enternal interface), enp2s0 (internal interface to LAN) and hurricane-ipv6 (interface to HE):

enp1s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet  netmask  broadcast
        inet6 fe80::219:5bff:fe2f:e30  prefixlen 64  scopeid 0x20<link>
        inet6 2001:470:1f16:204::2  prefixlen 64  scopeid 0x0<global> ...

enp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet  netmask  broadcast
        inet6 2001:470:1f17:204:21f:c6ff:fe5e:58b1  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::21f:c6ff:fe5e:58b1  prefixlen 64  scopeid 0x20<link> ...

hurricane-ipv6: flags=209<UP,POINTOPOINT,RUNNING,NOARP>  mtu 1480
        inet6 fe80::b847:c15a  prefixlen 64  scopeid 0x20<link>
        inet6 2001:470:1f16:204::2  prefixlen 64  scopeid 0x0<global>...

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet  netmask
        inet6 ::1  prefixlen 128  …
how to send and receive the message through in tcp/ip using servlet

I have an interesting setup. We switched to a hosted voip solution but for our emergency analogue lines we purchased two fxs vega 3050g gateways.

I have successfully configured the dialplans between the two units without the freepbx box as an in between. It is such a simple setup to just have it dial our security desk the pbx was not needed.

We are getting ready to deploy but have two lingering issues. To route calls between interfaces and the two gateway devices you have to initiate the sip handler to apply codecs and handle advanced features like call waiting. So dialing by IP between devices or loopback on between interfaces.

The one limitation I am running into is only one call at a time will take place between gateway... almost like the port is busy or it can only route one call at a time between gateways. Similar issue happens when trying to use call waiting... the first call connects but when I initiate the second call I get one indicator tone then the call fails with a cause code 41 (temporary network error)

Is this a matter of me needing to use more than the default udp port 5060 or am I just missing something here? I'm not a phone guy so I have a slight learning deficit.

I have combed through sangomas support site and manuals and found nothing like this... their support has yet to offer any solutions (on almost any of the setup.. which is troubling) so I'm turning to the community.

Thank you in advance
I am able to send email to gmail (of course) although it does show up as spam, outlook flatly rejects the .loc domain... but still cannot send between two .loc domains in lab..

I created two domains, dc2016.loc and dc2016a.loc (using 2016 essentials as DC) I have added both domains to the accepted domains list however, when I attempt to send to either of the two .loc domains, the email gets rejected as, unable to locate a valid address...

Looking at the recipient Information in the Queue Viewer, I am seeing Last Error: [{LRT=};{LED=};{FQDN=};{IP=}] even thought I have added them as accepted domains...Any thoughts?

I have just added a virtual private NIC to both exchange servers, and added appropriate send receive connectors on each

I have both NICs setup to Enable NetBIOS over TCP/IP as well but still having this issue... any thoughts?
(1) how can i know subnet mask & default gateway of any ipv4?
(2)Explain  dns server in detail?
devices behind a switch are not able to acquire DHCP. when i assign a static IP it works OK.  the switch is connected by fiber optic to a core switch where the DHCP is configured
I had this question after viewing SonicWall SOHO VPN site to site setup.

ID: 415306722016-03-3
If that is the case then you want the IP Address of the SOHO to be the Gateway address of the Comcast and the Gateway Address of the SOHO to be the IP Address of the Comcast. Then when you set up the the VPN you set it up with the IP Addresses of the SOHOs. Seems a little weird but that is the way it is done."
we have a TZ-210 wireless that need to change a couple of things on.  

We are connected to a comcast business gateway device.  It has wireless and we use that as an outside wireless,  It is not setup to access the internal network.  When we setup a laptop of phone we use that for VPN testing and remote connectivity.  I have 2 issues.

1. I cannot connect to the management interface on the modem, it is the default  It keeps getting dropped in the firewall.  What rukes do I add to tallow this?
2. We cannot send email from our mobile devices when connected to the Comcast wireless.  I would expect it to be a rule as well, but I'm not sure what to add to make this work.

We want to keep the comcast wireless off the internal network. But we need to access the management interface, plus some of the users need to be able to send via exchange when using devices or phones and sending exchange email.

I have 5 IP's assigned by AT&T to me on my On Demand Fiber circuit, but I only have 1 public address to the WAN. How do configure my 3 TZ300 to each use one of the assigned IP address and each to be a DHCP server?
ATEN's HDBaseT Presentation at InfoComm 2017
ATEN's HDBaseT Presentation at InfoComm 2017

Hear ATEN Product Manager YT Liang review HDBaseT technology, highlighting ATEN’s latest solutions as they relate to real-world applications during her presentation at the HDBaseT booth at InfoComm 2017.

Here's my scenario.  I have two networks and I need to combine them, ideally using Cisco SG300.  
Basically, LAN1 nodes need to be accessible to the LAN2 devices.  
To be exact, LAN2 computers need to be able to "talk" (TCP inbound and outbound) to the LAN1 computers on different ports.

Please see the diagram.  

I think I need to create two VLANS but not sure about the details.  Is this even possible with this switch?


I have TDA200  I have made no restriction for Landline & Mobile and restrictions for International calls

I want to know...for dialing an international call it should be in such a way that they should be able to dial it with Code only. I want

to know the steps how to do it
I have a client who uses cloud hosted VOIP service provided by a respected uk based voip provider.

My client is based in a managed office where the network is managed by a 3rd party company. My clients has been experienceing intermittant issues with the phones and they have asked the network people to check that the firewall\router\vlan configuration is suitable  for voip traffic.

The network people have come back saying :
I have reviewed the data captured yesterday, the problem IP address 109.*.*.70 is registered to THE VOIP PROVIDER. This is passing tiny data fragments through the firewall which is flagged as a security threat as this method is also used to hack routers and firewalls, this throws up an alarm and is blocked.

They have suggested we ask the VOIP provider why this is happeneing.

I am not a networking or VOIP expert. Can someone explain more about this and perhaps suggest why these "tiny data fragments" might be occuring?
ipconfig \ all =>

Two IPv6 addresses, one is temperate with me from the speed test , question :  who is holding the first IPv6 ?  ISP or Unknown ?
where to find its mac address ?  Could it be rewritten my computer mac then, getting the 1st IPv6 then release the 2nd IPv6 to my modem while from IPv4 both sharing the same public IP by ISP .

two IPv6 who is first IPv6 where find its mac address ?
I have a EPC3940 Wifi-router, but its reach is insufficient and so I want to add an access point (DAP2553). It is already connected, and it has an SSID, and it gives IP-addresses to phones and tablets (or probably the dhcp server in the router does that).
I want to configure a few things on the access point but I cannot get in the configuration page which is supposed to be at

The IP-addresses on my LAN are currently
Internet IP Address: / 24
Subnet Mask:
DHCP Server:       Enabled
Starting IP Address:
End IP Address:

Please tell me what to do

A last remark. The access point (DAP2553) is connected to my router and functions, it gets an IP-address from my dhcp, but I cannot configure it. Also
I have a network using subnet mask, and the adresses are 192.168.x.x, the Gateway has the ip address

We are experiencing a routing issue with segment 1. For instance, we need to print from a server to a workstation, the server has the ip, and the station is

A ping from to goes timeout. A traceroute shows a route going trough the Gateway despite the subnet mask.

Any clues?






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.