name:                    "large request edns",
			host:                    "giant.",
			expectResolutionFailure: dns.RcodeSuccess,
			expected:                giantResponse,
			modifyReq: func(msg *dns.Msg) {
				msg.SetEdns0(dns.MaxMsgSize, false)
			},
		},
		{
			name:                    "large request truncated",
			host:                    "giant-tc.",
			expectResolutionFailure: dns.RcodeSuccess,

		return 0, nil, nil, err
	}

	// Accept packets up to maxDNSPacketSize.  RFC 6891.
	if err := b.StartAdditionals(); err != nil {
		return 0, nil, nil, err
	}
	var rh dnsmessage.ResourceHeader
	if err := rh.SetEDNS0(maxDNSPacketSize, dnsmessage.RCodeSuccess, false); err != nil {
		return 0, nil, nil, err
	}
	if err := b.OPTResource(rh, dnsmessage.OPTResource{}); err != nil {
		return 0, nil, nil, err
	}