Amer Networks SS3GR24i - Manual (Page 48)

SS3GR24i/SS3GR48i Layer3 Stackable Gigabit Switch User’s Guide
Figure 5-4. Ethernet Packet Header
The UDP header is shorter than a TCP header. UDP also uses a
checksum to verify that data is received uncorrupted.
The Internet Control Message Protocol (ICMP) is also a simplified
protocol used for error messages and messages used by TCP/IP.
ICMP, like UDP, processes messages that will fit into a single
packet. ICMP does not, however use ports because its messages are
processed by the network software.
The Domain Name System
Computer users usually prefer to use text names for computers
they may want to open a connection with. Computers themselves
require 32 bit IP addresses. Somewhere, a database of network
devices’ text names and their corresponding IP addresses must be
maintained.
The Domain Name System (DNS) is used to map names to IP
addresses throughout the Internet and has been adapted for use
within intranets.
For two DNS servers to communicate across different subnets, the
DNS Relay of the SS3GR24i/SS3GR48i must be used. The DNS
servers are identified by IP addresses.
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