Siemens SIMATIC ET 200AL, System Manual

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Addressing via DHCP
10.2 DHCP with DNS
Communication
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Function Manual, 05/2021, A5E03735815-AJ
How you set the DNS configuration for your CPU depends on how you assign the host name
and domain in your network .
•
Central assignment of host name and domain
You assign the host name and domain centrally in your network, for example via a
configured DNS server. In STEP 7 you configure that the CPU obtains the host name and
domain via DHCP.
In the following configuration, only the client ID is configured in the S7-1500 CPU. At the
DHCP address assignment the DHCP-server returns the host name and domain options to
the CPU.
Figure 10-3 Obtain host and domain name via DHCP
For this configuration, you must first activate the host name and domain configuration in
STEP 7. You then configure that the host and domain name are obtained via DHCP.
Obtain host and domain name via DHCP (Page 371)
• Local assignment of host name and domain
You can configure the host name and domain in STEP 7 or assign them in the user
program.
Note
Validity of the data obtained from DHCP
If you change the host name and/or domain in the user program, then all data obtained
via DHCP (IP suite, host name, domain, NTP server, DNS server) becomes invalid and is
retrieved again from DHCP server. Therefore, you should only change the Hostname
and/or Domain in urgent cases and not during operation.
All connections can be dropped if the IP address of the interface changes.