using System; /* http://tools.ietf.org/rfc/rfc1183.txt 3.3. The Route Through RR The Route Through RR is defined with mnemonic RT and type code 21 (decimal). The RT resource record provides a route-through binding for hosts that do not have their own direct wide area network addresses. It is used in much the same way as the MX RR. RT has the following format: RT Both RDATA fields are required in all RT RRs. The first field, , is a 16 bit integer, representing the preference of the route. Smaller numbers indicate more preferred routes. is the domain name of a host which will serve as an intermediate in reaching the host specified by . The DNS RRs associated with are expected to include at least one A, X25, or ISDN record. The format of the RT RR is class insensitive. RT records cause type X25, ISDN, and A additional section processing for . For example, sh.prime.com. IN RT 2 Relay.Prime.COM. IN RT 10 NET.Prime.COM. *.prime.com. IN RT 90 Relay.Prime.COM. When a host is looking up DNS records to attempt to route a datagram, it first looks for RT records for the destination host, which point to hosts with address records (A, X25, ISDN) compatible with the wide area networks available to the host. If it is itself in the set of RT records, it discards any RTs with preferences higher or equal to its own. If there are no (remaining) RTs, it can then use address records of the destination itself. Wild-card RTs are used exactly as are wild-card MXs. RT's do not "chain"; that is, it is not valid to use the RT RRs found for a host referred to by an RT. The concrete encoding is identical to the MX RR. */ namespace Heijden.DNS { public class RecordRT : Record { public ushort PREFERENCE; public string INTERMEDIATEHOST; public RecordRT(RecordReader rr) { PREFERENCE = rr.ReadUInt16(); INTERMEDIATEHOST = rr.ReadDomainName(); } public override string ToString() { return string.Format("{0} {1}", PREFERENCE, INTERMEDIATEHOST); } } }