Chapter 2 DNS Concepts. If you already understand what DNS is and does and how it fits into the greater scheme of things skip this chapter. A brief History of Name Servers. DNS Concepts Implementation. In a post a couple of years ago I gave an example on how to configure an Ubuntu 12. Active Directory. Things used to be hard back then. DNS, BIND, DHCP, LDAP and Directory Services. BIND Berkeley Internet Name Domain is an implementation of the DNS protocols and provides an openly redistributable. DNS Overview. 2. 2. Domains and Delegation. DNS Organization and Structure. DNS System Components. Zones and Zone Files. DNS Queries. 2. 2. Recursive Queries. Iterative Queries. Inverse Queries. 2. Arabic Font Pack 1200 Ttf here. Zone Updates. 2. 2. Full Zone Transfer AXFR2. Incremental Zone Transfer IXFR2. Find Active Directory Bind Dns' title='Find Active Directory Bind Dns' />Notify NOTIFY2. Dynamic Zone Updates. Alternative Dynamic DNS Approaches. DNS Security Overview. Security Threats. Security Types. 2. Local Security. 2. Server Server TSIG Transactions2. Server Client DNSSEC2. A brief History of Name Servers. DNS Concepts. If you already understand what DNS is and does and how it fits into the greater scheme of things skip this chapter. A brief History of Name Servers. Here is a collection of info on how to access Active Directory using JAVA for tasks like User and Group management, and authentication. I seem to be unable to use php to securely bind to Active Directory. Unencrypted connections work fine. Using other clients are able to securely bind, e. Schema AccountExpires accountExpires 2. AccountNameHistory accountNameHistory 2. ACSAggregateTokenRatePerUser aCSAggregateTokenRatePerUser. DNS servers Without a Name Service there would simply not be a viable Internet. To understand why, we need to look at what DNS does and how and why it evolved. A DNS translates or maps the name of a resource to its physical IP address typically referred to as forward mapping. A DNS can also translate the physical IP address to the name of a resource typically called reverse mapping. Big deal. Remember that the Internet or any network for that matter works by allocating every point host, server, router, interface etc. IP address which may be locally unique or globally unique. Separation of Church and State. Without DNS every host PC which wanted to access a resource on the network Internet, say a simple web page, for example, www. IP address. With 1. To solve this problem the concept of Name Servers was created in the mid 7. Name Server. With a Name Server present in the network any host only needs to know the physical address of a Name Server and the name of the resource it wishes to access. Using this data it can find the address or any other stored attribute or property of the resource by interrogating querying the Name Server. Resources can be added, moved, changed or deleted at a single location the Name Server. At a stroke network management was simplified and made more dynamic. If its broke. We now have a new problem with our newly created Name Server concept. If our Name Server is not working our host cannot access any resource on the network. We have made the Name Server a critical resource. So we had better have more than one Name Server in case of failure. To fix this problem the concept of Primary and Secondary Name Servers many systems allow tertiary or more Name Servers was born. If the Primary Name Server does not respond a host can use the Secondary or tertiary etc. Man, we got more names than Webster. As our network grows we start to build up a serious number of Names in our Name Server database. This gives rise to three new problems. Finding any entry in the database of names becomes increasingly slow as we power through many millions of names looking for the one we want. We need a way to index or organize the names. If every host is accessing our Name Servers the load becomes very high. Maybe we need a way to spread the load across a number of servers. With many Name resource records in our database the management problem becomes increasingly difficult as everyone tries to update all the records at the same time. Maybe we need a way to separate or delegate the administration of these Name resource records. Which leads us nicely into the characteristics of the Internets Domain Name System DNS. The Internets Domain Name Service DNS is just a specific implementation of the Name Server concept optimized for the prevailing conditions on the Internet. DNS Overview. From our brief history of Name Servers we saw how three needs emerged The need for a hierarchy of names. The need to spread the operational loads on our name servers. The need to delegate the administration of our Name servers. The Internet Domain Name System elegantly solves all these problems at the single stroke of a pen well actually the whole of RFC 1. Domains and Delegation. The Domain Name System uses a tree or hierarchical name structure. At the top of the tree is the root. Top Level Domains TLDs then the domain name and any number of lower levels each separated with a dot. NOTE The root of the tree is represented most of the time as a silent dot. Top Level Domains TLDs are split into two types. Generic Top Level Domains g. TLD. com,. edu,. Country Code Top Level Domain cc. TLD e. g. us,. Country Code TLDs cc. TLDs use a standard two letter sequence defined by ISO 3. Since 2. 00. 4 g. TLDs now have a sub category known as s. TLDs Sponsored TLDs which implies they have limited registration, examples of s. TLDs include. aero,. TLDs typically have open registration requirements. Finally, since 2. TLD policy is essentially unrestricted, if you pay enough money and adopt the operating procedures laid down anyone can register a sponsored TLD. Look forward to a whole set of new TLDs like. Figure 1 1 shows this diagrammatically. Figure 1 1 Domain Structure and Delegation. What is commonly called a Domain Name is actually a combination of a domain name and a TLD and is written from LEFT to RIGHT with the lowest level in the hierarchy on the left and the highest level on the right. In the case of the g. TLDs, such as. com,. Second Level Domain SLD. It is the second level in the hierarchy. The user part is therefore frequently simply referred to as the SLD. So the the Domain Name in the example above can be re defined to consist of. The term Second Level Domain SLD is much less useful with cc. TLDs where the user registered part is typically the Third Level Domain, for example. The term Second Level Domain SLD provides technical precision but can be confusing when applied to a generic concept like a user domain unless the precision is required we will continue to use the generic term Domain Name or simply Domain to describe the whole name, for instance, what this guide calls a Domain Name would be example. Authority and Delegation. The concepts of Delegation and Authority lie at the core of the domain name system hierarchy. The Authority for the root domain lies with Internet Corporation for Assigned Numbers and Names ICANN. Since 1. 99. 8 ICANN, a non profit organisation, has assumed this responsibility from the US government. The g. TLDs are authoritatively administered by ICANN and delegated to a series of accredited registrars. The cc. TLDs are delegated to the individual countries for administration purposes. Figure 1. 0 above shows how any authority may in turn delegate to lower levels in the hierarchy, in other words it may delegate anything for which it is authoritative. Each layer in the hierarchy may delegate the authoritative control to the next lower level. In the case of cc. TLDs countries like Canada cc. TLD. ca and the US cc. TLD. us and others with federal governments decided that they would administer at the national level and delegate to each province Canada or state US a two character provincestate code, for example,. Quebec,. ny New York, md Maryland etc. Thus mycompany. md. Domain Name of mycompany which was delegated from the state of Mary. Land in the US. This was the delegation model until around 2. Thus, today you can register mycompany. The old delegation models are still valid and you still domains such as quebec.