The purpose of this special issue is to assemble a selection of best research articles that were presented within the 6th International Conference on Innovative Network Systems and Applications (iNetSApp'18), 1 which was organized under the Federated Conference on Computer Science and Information Systems 2018 (FedCSIS'18), 2 which was held in the Polish city Pozna ń. According to the FedCSIS policy, 23% acceptance rate was kept in all regular paper submissions with the help of the well-structured and experienced conference program committee. Since only the little amount of papers met the quality for the publication in this special issue, other selected best papers from the 18th International Conference on Innovations for Community Services (I4CS 2018), 3 which was held in Žilina, Slovakia, were selected for the publication. For this special issue, only the papers with best review score were selected, thus the quality of the CPE series can be conserved.This special issue focuses on different applications and algorithm developments in the area of modern network systems which encompass a wide range of solutions and technologies, including wireless and wired networks, network systems, services, and applications. The scope of this special issue is broad, aiming at different results in numerous active research areas oriented toward various technical, scientific, and social aspects of network systems and applications. This is supplied by the recent advances in the theory and practice in a wide range of aspects of Internet community services, especially of how community services can be used in many areas and how they have been deployed.The authors in Reference 4 focused on the improvements of the convergence time in IP networks. They introduced a new kind of IP fast re-route (IPFRR) mechanism called the multicast repair (MREP) IPFRR mechanism, which provides an advanced fast reroute technique for Internet service providers' core networks. The M-REP IPFRR mechanism is based on IP multicast and utilizes Protocol Independent Multicast-Dense Mode with the modification of an internal reverse path forwarding check. The M-REP IPFRR mechanism does not depend on any particular routing protocol type (distance-vector or link-state) and requires less system resources because of its precomputation-less character but still provides immediate reaction to failure.The article 5 dealt with the problematic of the work with the large datasets. The article proposed a Flower Index Approach as the method for dealing with the data processing. With this approach, it was possible to remove the impact of the High-Water Mark, as well as to remove useless block loading with no relevant data. On the other hand, it provided effective data access stream using a specific index. Full Table Scan could be the skipped and data could be accessed directly using the index ROWID locators.Data reliability with temporal data retrieval was discussed in the article. 6 The authors referenced an attribute-oriented temporal model with reflection on data grouping tech...