Many of you have already heard about it or even used it once in a while, but most of you have probably not been introduced to it yet: Our rescue system! While hopefully not being needed at all, it provides many possibilities to fix certain problems and to bring the machine back online as soon as possible. When the server is down, every second counts. It is important to know what to do beforehand. Thus, I will provide you with some basic information first:
With a Service Resource Record (short: SRV record) you can make services, which are usually available via an IP:PORT combination, reachable using a DNS host name. Important to note regarding SRV record is the fact, that they only work if an application has been specifically programmed to make use of them. Examples for this are TeamSpeak3 or Minecraft. SRV-Records can not be used to point a DNS name to an IP address/port combination for arbitrary use by any application.
Example – Teamspeak:
Usually TeamSpeak is using the protocol UDP over port 9987. If you are running a TeamSpeak instance with the IP 123.124.125.126 every client that wants to connect has to enter the IP:port combination of 123.124.125.126:9987. If you change the port or the server IP, you have to inform everyone about the new combination. With SRV records it is possible to connect to TeamSpeak using a DNS host name like ts.mydomain.com
