using System;

using System.Linq;

using System.Collections.Generic;

using System.Xml.Linq;

public class Program

{

    public class Record

    {

        public int Id { get; set; }

​

        public string Name { get; set; }        

        public int Code { get; set; }

​

        public string Domain { get; set; }

    }

    public static void Main()

    {

        var filter = new List<Record>()

           {

               new Record { Id = 011, Name = "OAKLAWN", Code = 123, Domain = "p1000"},

               new Record { Id = 012, Name = "OAKLAWN", Code = 124 , Domain = "p2000"},

               new Record { Id = 013, Name = "OAKLAWN", Code = 125 , Domain = "p3000"},

               new Record { Id = 014, Name = "OAKLAWN", Code = 126 , Domain = "p2000"},

               new Record { Id = 015, Name = "OAKLAWN", Code = 127 , Domain = "p5000"},

               new Record { Id = 016, Name = "PEAKLAWN", Code = 111 , Domain = "p6000"},

               new Record { Id = 017, Name = "PERKLAWN", Code = 124 , Domain = "p6000"},

               new Record { Id = 018, Name = "QUCKLAWN", Code = 122 , Domain = "p6000"}

           };

        var records = filter.GroupBy(t => t.Name).Where(x => x.Name.ToLower().Contains("OAK")).ToList();

            records.Dump();

​

    }   

}