Wireshark Lab 3 DNS | Maxwell Sullivan: Computer Science
Jul 11, 2015 When does DNS use TCP or UDP? - Network Interview Apr 04, 2020 DNS Flag Day 2020: DNS servers must support both UDP and May 22, 2019
DNS resolvers and recursive servers MUST support UDP, and SHOULD support TCP, for sending (non-zone-transfer) queries. However, some implementors have taken the text quoted above to mean that TCP support is an optional feature of the DNS protocol.
Oct 31, 2009 · DNS uses UDP for DNS Queries over Port: 53. A client computer will always send a DNS Query using UDP Protocol over Port 53. If a client computer does not get response from a DNS Server, it must re-transmit the DNS Query using the TCP after 3-5 seconds of interval. For example: IP fragmentation for larger DNS answers that do not fit into a single UDP datagram (hopefully not after the DNS flag day 2020 anymore), or DNS via TCP, or some newer options within the EDNS space such as “EDNS Client Subnet” (ECS) or DNS cookies. Jul 03, 2017 · TCP and UDP aren’t the only protocols that work on top of IP. However, they are the most widely used. How TCP Works. TCP is the most commonly used protocol on the Internet. When you request a web page in your browser, your computer sends TCP packets to the web server’s address, asking it to send the web page back to you. Security practitioners for decades have advised people to limit DNS queries against their DNS servers to only use UDP port 53. The reality is that DNS queries can also use TCP port 53 if UDP port
access-list 200 permit udp any eq domain any. also "ip inspect Firewall out " for tcp , udp, ftp. ok. Everything works fine as i have "ip dns server" globally enabled (as like a proxy for my internal net) But now the issue seems that my port 53 udp is open and everyone ( isp said this) could use this DNS for some attacks and so on.
Is DNS TCP or UDP Port 53? | Infoblox DNS Security Center FAQ The answer is DNS is mostly UDP Port 53, but as time progresses, DNS will rely on TCP Port 53 more heavily. DNS has always been designed to use both UDP and TCP port 53 from the start 1 , with UDP being the default, and fall back to using TCP when it is unable to communicate on UDP, typically when the packet size is too large to push through in a single UDP packet. Why does DNS use UDP and not TCP? - GeeksforGeeks Jul 11, 2015 When does DNS use TCP or UDP? - Network Interview