How to change the hostname was set/defined in SAP system?

Question

Dear Expert,
My customer met a problem about that:
he defined his host name with small characters(lower case) "abc" when he installed the SAP system (Windows2003(x64)-Solman70SR4).
But in SM21, the title of sm21, the hostname was recognize as upper case "ABC".
in SM51, the hostname was also recognized as upper case "ABC"
in STMS, the tab of 'transport tool', it is recognized as lower case "abc" in TRANSDIR.
in SM59, it is recognized as upper case "ABC" in internal connections, but recognized as lower case "abc" in ABAP connections, such as TMSADM@<DB>.DOMAIN.<sid>
While in Java URL, it is recognized as lower case "abc". With my test, the Java URL is not case sensitive for the HOSTNAME part in HTTP link as I tested to change the hostname both in upper case and lower case in etc\hostname file, the URL both are working. (not sure if this is due to the test is with intranet or not).
Based on SAP note 611361, it seems that:
"Hostnames must be considered "case sensitive". That means
hostnames shall be used in the same case (upper or lower) in all
SAP configurations as well as in the network configuration (DNS
or etc/hosts). You must ensure consistent name resolving of the
hostname from hostname to IP address and back from the IP address
to the the same hostname (case sensitive match). See also note
129997."
Please help to suggest.
Many thanks in advance,
Perry Song

Answer 1

Section  4.13 "Checking the Consistency of the Host Name" in [This Upgrade Guide|https://websmp208.sap-ag.de/~sapidb/011000358700000353422008E]  has a good explaination of what & how to check your hostname / parameter configuration.
on a windows box, another way to get the TCP/IP name is to type  'hostname' from a CMD window.