Improve RandomDnsTest to avoid having a too long packet.
Improve RandomDnsTest to avoid having a too long packet.

bricknerb/Pcap.Net,petredimov/Pcap.Net,petredimov/Pcap.Net,bricknerb/Pcap.Net,suarez-duran-m/pcap-pade,OperatorOverload/Pcap.Net,prvillagra/Pcap.Net,OperatorOverload/Pcap.Net,prvillagra/Pcap.Net,giokats/Pcap.Net,prvillagra/Pcap.Net,suarez-duran-m/pcap-pade,OperatorOverload/Pcap.Net,petredimov/Pcap.Net,bricknerb/Pcap.Net,suarez-duran-m/pcap-pade,giokats/Pcap.Net,giokats/Pcap.Net