Biblio

Optical Code Division Multiple Access (OCDMA) is an inevitable innovation to cope up with the impediments of regularly expanding information traffic and numerous user accesses in optical systems. In Spectral Amplitude Coding (SAC)-OCDMA systems cross correlation and Multiple Access Interference (MAI) are utmost concerns. For eliminating the cross correlation, reducing the MAI and to enhance the security, in this work, all optical Diagonal Identity Matrices codes (DIM) with Zero Cross-Correlation (ZCC) and optical gating are presented. Chip rate of the proposed work is 0.03 ns and total 60 users are considered with semiconductor optical amplifier based AND operation. Effects of optical gating are analyzed in the presence/absence of eavesdropper in terms of Q factor and received extinction ratio. Proposed system has advantages for service provider because this is mapping free technique and can be easily designed for large number of users.

Top-level domains play an important role in domain name system. Close attention should be paid to security of top level domains. In this paper, we found many configuration anomalies of top-level domains by analyzing their resource records. We got resource records of top-level domains from root name servers and authoritative servers of top-level domains. By comparing these resource records, we observed the anomalies in top-level domains. For example, there are 8 servers shared by more than one hundred top-level domains; Some TTL fields or SERIAL fields of resource records obtained on each NS servers of the same top-level domain were inconsistent; some authoritative servers of top-level domains were unreachable. Those anomalies may affect the availability of top-level domains. We hope that these anomalies can draw top-level domain administrators' attention to security of top-level domains.