Return Mulitple values using c# code

You can do either of these:

1) Return back values using ref parameters

2) Return a struct containing the multiple return values

If you have .NET 4.0, then you have this option too:

3) Return a Tuple<>

Do not do either of these:

1) Return a concatenated string

2) Return an array

Both of these are not scalable and prone to error.

There are at least two other ways you could return a pair of strings.

1. Return one (or both) of them as an out parameter. Here, I'm returning both.

public void ReturnIp(string domainName, out string domainIP, out string status)
    {
    ....
    }

2. You could define a struct or class to carry the pair of strings as a single value, and return that an instance of that type (note that I'm including the domain name in the class, so that the name and IP address are always closely associated):

class DomainInfo
    {
    public string DomainName { get; set; }
    public string DomainIp { get; set; }
    public string Status { get; set; }
    }

...

public DomainInfo ReturnIp(string domainName)
    {
    ...
    return new DomainInfo { DomainName = domainName, DomainIp = ..., Status = ... };
    }

Your method of concatenating the two strings certainly works, but would be considered by many programmers to be bad form as it combines two distinct values into a single entity.

Please note - unless the status value you want to return is truly a text value, you might find the use of an enum to encode the set of possible status values is clearer (and will be definitely more reliable since it doesn't rely on text parsing / comparison to interpret).

As the others have said, out or if you need to pass a value in that the method may change ref parameters can work - this is the way methods such as int.TryParse do it.

Create a custom class that exposes the properties required and return an instance of that.

If it is multiples of the same data type, string in this case, that you need to return then you could return an array, a List<string>, ReadOnlyCollection<string> or even IEnumerable<string> etc.

A concantenated string that requires splitting later is normally a bad idea. The only time I would do anything even similar to that is if I were creating an XML file as a string, a CSV file or a line deliminated text file.