TCP 721

Looking for information on Protocol TCP 721? This page will attempt to provide you with as much port information as possible on TCP Port 721.

TCP Port 721 may use a defined protocol to communicate depending on the application. A protocol is a set of formalized rules that explains how data is communicated over a network. Think of it as the language spoken between computers to help them communicate more efficiently.

Protocol HTTP for example defines the format for communication between internet browsers and web sites. Another example is the IMAP protocol that defines the communication between IMAP email servers and clients or finally, the SSL protocol which states the format to use for encrypted communications.

TCP Port 721

Here is what we know about protocol TCP Port 721. If you have information on TCP port 721 that is not reflected on this page, simply leave a comment and we’ll update our information.

PORT 721 – Information

• Port Number: 721
• TCP / UDP: TCP
• Delivery: Yes
• Protocol / Name: nt
• Port Description: Windows NT v3.5x Printer Ports. Print jobs from NT v3.5x hosts are sourced from tcp 721-731, sequentially. Changed under NT v4.0, the lpd client now uses random source port between 512 and 1023. Was changed to provide higher consecutive print volume.
• Virus / Trojan: No

  Tip! Use our free Digital Footprint and Firewall Test to help verify you are not infected.

Side note: TCP port 721 uses the Transmission Control Protocol. TCP is one of the main protocols in TCP/IP networks. Whereas the IP protocol deals only with packets, TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and also guarantees that packets will be delivered on port 721 in the same order in which they were sent. Guaranteed communication over port 721 is the key difference between TCP and UDP. UDP port 721 would not have guaranteed communication in the same way as TCP.

Because protocol TCP port 721 was flagged as a virus (colored red) does not mean that a virus is using port 721, but that a Trojan or Virus has used this port in the past to communicate.

TCP 721 – Disclaimer

We do our best to provide you with accurate information on PORT 721 and work hard to keep our database up to date. This is a free service and accuracy is not guaranteed. We do our best to correct any errors and welcome feedback!