The `servers.ToList()` seems unnecessary

[GF-Huang]

DnsClient.NET/src/DnsClient/LookupClient.cs

Line 555 in 20b0ac4

var result = ResolveQuery(servers.ToList(), queryOptions, handler, request, audit);

Change the param from IReadOnlyCollection<NameServer> servers to IReadOnlyList<NameServer> servers maybe better.

DnsClient.NET/src/DnsClient/LookupClient.cs

Line 526 in 20b0ac4

private IDnsQueryResponse QueryInternal(DnsQuestion question, DnsQuerySettings queryOptions, IReadOnlyCollection<NameServer> servers)