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Which service use both TCP and UDP ports?

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Question added by Muhammad Irfan , Level II Enterprise Services Engineer , Machsol,Inc
Date Posted: 2016/06/29
Syed Faizan Ahmed
by Syed Faizan Ahmed , IT Administrator , SHUAIBA INDUSTRIAL COMPANY.

DNS and some other services work on both the protocols. We will take an example of DNS Service. Two protocols are somewhat different from each other. TCP is a connection-oriented protocol and it requires data to be consistent at the destination and UDP is connection-less protocol and doesn't require data to be consistent or don't need a connection to be established with host for consistency of data.

UDP packets are smaller in size. UDP packets can not be greater then 512 bytes. So any application needs data to be transferred greater than 512 bytes require TCP in place. For example, DNS uses both TCP and UDP for valid reasons described below. Note that UDP messages are not larger than 512 Bytes and are truncated when greater than this size.  DNS uses TCP for Zone transfer and UDP for name queries either regular (primary) or reverse. UDP can be used to exchange small information whereas TCP must be used to exchange information larger than 512 bytes. If a client doesn't get response from DNS it must re-transmit the data using TCP after 3-5 seconds of interval.

There should be consistency in DNS Zone database. To make this, DNS always transfer Zone data using TCP because TCP is reliable and make sure zone data is consistent by transferring the full zone to other DNS servers who has requested the data.

The problem occurs when Windows 2000 server and Advanced Server products uses Dynamic ports for all above 1023. In this case your DNS server should not be internet facing i.e. doing all standard queries for client machines on the network. The router (ACL) must permitted all UDP inbound traffic to access any high UDP ports for it to work.

LDAP always uses TCP - this is true and why not UDP because a secure connection is established between client and server to send the data and this can be done only using TCP not UDP. UDP is only used when finding a domain controller (Kerberos) for authentication. For example, a domain client finding a domain controller using DNS.

Muhammad Irfan
by Muhammad Irfan , Level II Enterprise Services Engineer , Machsol,Inc

TCP protocal is used for DNS Zone transfer between two DNS servers. both servers establish a connection transfer data(zone data) and both Server will make sure that data is consistent via TCP connection.

On other Hand:  Connection between the DNS Server and client is using  UDP protocal over Port 53.  

muhammad usman Rasheed
by muhammad usman Rasheed , Technical Support Engineer , Abdul Rahman Alshareef

DNS Uses TCP for Zone Transfer overe port 53 and UDP port 53 for DNS quaries from client machines

poornima choudhary
by poornima choudhary , product manager , Artbugs Ventures LLP ( www.artbugs

DNS service work on both the protocol

Syed Maqsood Ali
by Syed Maqsood Ali , IT System Administrator , Al Sharq Steel Factory

DNS (Domain Naming System)

Mohammed Ibrahim
by Mohammed Ibrahim , system administrator , Almeera

DNS and some other services uses both TCP and UDP the reason for using both protocols is very simple as UDP is a connection less protocol and it does not acknowledge so it is slightly faster then TCP 

Hence DNS uses UDP for name queries wherein TCP for Zone transfer

Mohammad Yasin
by Mohammad Yasin , Desktop Support Engg , Progressive Info vision Pvt. Ltd

DNS and some other Services work on both the TCP and UDP Protocols. 

DNS uses TCP for Zone Transfer over Port: 53

Iftikhar Bacha
by Iftikhar Bacha , Implementation Quality Assurance Expert , Ooredoo - Oman

TCP protocal is used for DNS Zone transfer between two DNS servers.

Connection between the DNS Server and client is using  UDP protocal over Port 53.

michel adel aziz slama slama
by michel adel aziz slama slama , Network and System Administrator , GrandMall

DNS service use both tcp and udp ports

Rameez Rasool
by Rameez Rasool , Network Engineer , IBM India Pvt Ltd

Both TCP & UDP on port 53

TCP protocal is used for DNS Zone transfer between two DNS servers. both servers establish a connection transfer data(zone data) and both Server will make sure that data is consistent via TCP connection.

Isaf PT
by Isaf PT , Technical Support Specialist , Fleet Tracking Technologies Co. Ltd

DNS is widely use sevices of both TCP and UDP ports.

UDP is used when the size of the message is lessthan 512 bytes.

If the size is more than 512 bytes, then TCP will use.

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