Heijden.DNS.Resolver.SearchInCache C# (CSharp) Method

        private DNSResponse SearchInCache(Question question)
        {
            if (!m_UseCache)
            {
                return null;
            }

            string strKey = question.QClass + "-" + question.QType + "-" + question.QName;

            //logger.Debug("Checking cache for " + strKey + ".");

            lock (m_lookupFailures)
            {
                if (m_lookupFailures.ContainsKey(strKey))
                {
                    //logger.Debug("DNS cache failed result found for " + strKey + ".");

                    if (DateTime.Now.Subtract(m_lookupFailures[strKey].TimeStamp).TotalSeconds < FAILURE_RETRY)
                    {
                        return m_lookupFailures[strKey];
                    }
                    else
                    {
                        m_lookupFailures.Remove(strKey);
                        return null;
                    }
                }
            }

            DNSResponse response = null;

            lock (m_ResponseCache)
            {
                if (!m_ResponseCache.ContainsKey(strKey))
                {
                    //logger.Debug("DNS cache no result found for " + strKey + ".");
                    return null;
                }

                response = m_ResponseCache[strKey];

                if (response.Answers.Count == 0)
                {
                    // A response should not have been cached with no answer records.
                    m_ResponseCache.Remove(strKey);
                    return null;
                }
            }

            //int TimeLived = (int)((DateTime.Now.Ticks - response.TimeStamp.Ticks) / TimeSpan.TicksPerSecond);
            int secondsLived = (int)(DateTime.Now.Subtract(response.TimeStamp).TotalSeconds % Int32.MaxValue);
            //logger.Debug("Seconds lived=" + secondsLived + ".");
            foreach (RR rr in response.RecordsRR)
            {
                //rr.TimeLived = TimeLived;
                // The TTL property calculates its actual time to live
                if (secondsLived >= rr.TTL)
                {
                    //logger.Debug("DNS cache out of date result found for " + strKey + ".");
                    return null; // out of date
                }
            }

            //logger.Debug("DNS cache curent result found for " + strKey + ".");
            return response;
        }