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69-851: The original design of the Domain Name System did not include any security features. It was conceived only as a scalable distributed system. The Domain Name System Security Extensions (DNSSEC) attempt to add security, while maintaining backward compatibility . RFC   3833 of 2004 documents some of the known threats to the DNS, and their solutions in DNSSEC. DNSSEC was designed to protect applications using DNS from accepting forged or manipulated DNS data, such as that created by DNS cache poisoning . All answers from DNSSEC protected zones are digitally signed . By checking

138-506: A man in the middle attack is going on, stripping the DNSSEC information and modifying the A records. Or, it could be a broken security-oblivious name server along the way that stripped the DO flag bit from the query or the RRSIG record from the answer. Or, it could be a configuration error. Next, it may be that there is not a domain name named "www.example.com", in which case instead of returning

207-520: A RRSIG record in the answer, there will be either an NSEC record or an NSEC3 record. These are "next secure" records that allow the resolver to prove that a domain name does not exist. The NSEC/NSEC3 records have RRSIG records, which can be verified as above. Finally, it may be that the "example.com" zone implements DNSSEC, but either the "com" zone or the root zone do not, creating an "island of security" which needs to be validated in some other way. As of 15 July 2010, deployment of DNSSEC to root

276-478: A complete authentication chain, an answer to a DNS lookup cannot be securely authenticated. To limit replay attacks, there are not only the normal DNS TTL values for caching purposes, but additional timestamps in RRSIG records to limit the validity of a signature. Unlike TTL values which are relative to when the records were sent, the timestamps are absolute. This means that all security-aware DNS resolvers must have clocks that are fairly closely in sync, say to within

345-472: A complex six-message protocol and a lot of data transfers to perform key changes for a child (DNS child zones had to send all of their data up to the parent, have the parent sign each record, and then send those signatures back to the child for the child to store in a SIG record). Also, public key changes could have absurd effects; for example, if the ".com" zone changed its public key, it would have to send 22 million records (because it would need to update all of

414-521: A few minutes. These timestamps imply that a zone must regularly be re-signed and re-distributed to secondary servers, or the signatures will be rejected by validating resolvers. DNSSEC involves many different keys, stored both in DNSKEY records, and from other sources to form trust anchors . In order to allow for replacement keys, a key rollover scheme is required. Typically, this involves first rolling out new keys in new DNSKEY records, in addition to

483-450: A parent and child zone. In the new approach, when a child's master public key changes, instead of having six messages for every record in the child, there is one simple message: the child sends the new public key to its parent (signed, of course). Parents simply store one master public key for each child; this is much more practical. This means that a little data is pushed to the parent, instead of massive amounts of data being exchanged between

552-419: A problem for online signing servers, which keep their keys available online. However, DNSSEC was designed around using offline computers to sign records so that zone-signing-keys could be kept in cold storage. This represents a problem when trying to authenticate responses to queries for non-existent domains since it is impossible to pre-generate a response to every possible hostname query. The initial solution

621-564: A result, ZSKs can be much shorter than KSKs and still offer the same level of protection while reducing the size of the RRSIG/DNSKEY records. When a new KSK is created, the DS record must be transferred to the parent zone and published there. The DS records use a message digest of the KSK instead of the complete key in order to keep the size of the records small. This is helpful for zones such as

690-550: A set of verified public keys for the DNS root zone which is the trusted third party . Domain owners generate their own keys, and upload them using their DNS control panel at their domain-name registrar, which in turn pushes the keys via secDNS to the zone operator (e.g., Verisign for .com) who signs and publishes them in DNS. DNS is implemented by the use of several resource records. To implement DNSSEC, several new DNS record types were created or adapted to use with DNSSEC: When DNSSEC

759-420: A stub resolver, and Windows Server 2008 R2 and Windows 7 in particular use a non-validating but DNSSEC-aware stub resolver. Using the chain of trust model, a Delegation Signer (DS) record in a parent domain ( DNS zone ) can be used to verify a DNSKEY record in a subdomain , which can then contain other DS records to verify further subdomains. Say that a recursive resolver such as an ISP name server wants to get

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828-544: A sum signal to left and right channels if both sum and difference signals are received. Without the requirement for backward compatibility, a simpler method could have been chosen. Full backward compatibility is particularly important in computer instruction set architectures , two of the most successful being the IBM 360 / 370 / 390 / Zseries families of mainframes, and the Intel x86 family of microprocessors . IBM announced

897-546: A zone before many others will want to adopt it. DNS servers must be updated with software that supports DNSSEC, and DNSSEC data must be created and added to the DNS zone data. A TCP/IP-using client must have their DNS resolver (client) updated before it can use DNSSEC's capabilities. What is more, any resolver must have, or have a way to acquire, at least one public key that it can trust before it can start using DNSSEC. DNSSEC implementation can add significant load to some DNS servers. Common DNSSEC-signed responses are far larger than

966-499: Is forward compatibility ; a design that is forward-compatible usually has a roadmap for compatibility with future standards and products. A simple example of both backward and forward compatibility is the introduction of FM radio in stereo . FM radio was initially mono , with only one audio channel represented by one signal . With the introduction of two-channel stereo FM radio, many listeners had only mono FM receivers. Forward compatibility for mono receivers with stereo signals

1035-536: Is a critical and fundamental Internet service, yet in 1990 Steve Bellovin discovered serious security flaws in it. Research into securing it began, and progressed dramatically when his paper was made public in 1995. The initial RFC 2065 was published by the IETF in 1997, and initial attempts to implement that specification led to a revised (and believed fully workable) specification in 1999 as IETF RFC 2535. Plans were made to deploy DNSSEC based on RFC 2535. Unfortunately,

1104-431: Is a property of an operating system , software, real-world product, or technology that allows for interoperability with an older legacy system , or with input designed for such a system. Modifying a system in a way that does not allow backward compatibility is sometimes called " breaking " backward compatibility. Such breaking usually incurs various types of costs, such as switching cost . A complementary concept

1173-472: Is also BCP 237. It is widely believed that securing the DNS is critically important for securing the Internet as a whole, but deployment of DNSSEC specifically has been hampered (As of 22 January 2010) by several difficulties: DNSSEC works by digitally signing records for DNS lookup using public-key cryptography . The correct DNSKEY record is authenticated via a chain of trust , starting with

1242-446: Is also challenging. Ozment and Schechter observe that DNSSEC (and other technologies) has a "bootstrap problem": users typically only deploy a technology if they receive an immediate benefit, but if a minimal level of deployment is required before any users receive a benefit greater than their costs (as is true for DNSSEC), it is difficult to deploy. DNSSEC can be deployed at any level of a DNS hierarchy, but it must be widely available in

1311-415: Is attributed to its broad forward and backward compatibility; it became more popular than other standards that were not backward compatible. In software development, backward compatibility is a general notion of interoperation between software pieces that will not produce any errors when its functionality is invoked via API . The software is considered stable when its API that is used to invoke functions

1380-470: Is completed. The .com domain was signed with valid security keys and the secure delegation was added to the root zone on 1 April 2011. Stub resolvers are "minimal DNS resolvers that use recursive query mode to offload most of the work of DNS resolution to a recursive name server." A stub resolver will simply forward a request to a recursive name server, and use the Authenticated Data (AD) bit in

1449-401: Is ongoing to deploy DNSSEC, because the Internet is so vital to so many organizations. Early adopters include Brazil ( .br ), Bulgaria ( .bg ), Czech Republic ( .cz ), Namibia ( .na ) Puerto Rico ( .pr ) and Sweden ( .se ), who use DNSSEC for their country code top-level domains ; RIPE NCC , who have signed all the reverse lookup records (in-addr.arpa) that are delegated to it from

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1518-472: Is published in RFC4033-4035. In January 2024, a "KeyTrap" denial-of-service attack was announced for all specification-respecting DNSSEC resolvers. The DNSSEC specification (RFC4033-4035) specifies that a resolver, when receiving a signed packet from the upstream, should try all keys with the correct "tag" on all signatures until one of the combinations successfully verifies. By putting many keys with

1587-429: Is said to be backward compatible when a newer version of the program can open it without errors just like its predecessor. There are several incentives for a company to implement backward compatibility. Backward compatibility can be used to preserve older software that would have otherwise been lost when a manufacturer decides to stop supporting older hardware. Classic video games are a common example used when discussing

1656-418: Is stable across different versions. In operating systems, upgrades to newer versions are said to be backward compatible if executables and other files from the previous versions will work as usual. In compilers , backward compatibility may refer to the ability of a compiler for a newer version of the language to accept source code of programs or data that worked under the previous version. A data format

1725-455: Is used in the authentication of DNSKEYs in the lookup procedure using the chain of trust. NSEC and NSEC3 records are used for robust resistance against spoofing. DNSSEC was designed to be extensible so that as attacks are discovered against existing algorithms, new ones can be introduced in a backward-compatible fashion as described in RFC   8624 . The following table defines, as of June 2019,

1794-428: Is used, each answer to a DNS lookup contains an RRSIG DNS record, in addition to the record type that was requested. The RRSIG record is a digital signature of the answer DNS resource record set. The digital signature is verified by locating the correct public key found in a DNSKEY record. The NSEC and NSEC3 records are used to provide cryptographic evidence of the non-existence of any Resource Record (RR). The DS record

1863-625: The .com domain, which are very large. The procedure to update DS keys in the parent zone is also simpler than earlier DNSSEC versions that required DNSKEY records to be in the parent zone. A closely related principle is that of Algorithm rollover , this involves migrating a zone from one signing Algorithm to another. A good example of this would be migrating from Algorithm 8 (RSA/SHA-256) to Algorithm 13 (ECDSA/SHA-256). Several ccTLD's have already migrated including .at , .br , .cz , .ch , .fr , .ie , .nl and .ph . Verisign migrated .com, .net and .edu to Algorithm 13 in late 2023. The migration of

1932-511: The Internet Assigned Numbers Authority (IANA). ARIN is also signing their reverse zones. In February 2007, TDC became the first Swedish ISP to start offering this feature to its customers. IANA publicly tested a sample signed root since June 2007. During this period prior to the production signing of the root, there were also several alternative trust anchors. The IKS Jena introduced one on January 19, 2006,

2001-527: The Internet Systems Consortium introduced another on March 27 of the same year, while ICANN themselves announced a third on February 17, 2009. On June 2, 2009, Afilias , the registry service provider for Public Interest Registry 's .org zone signed the .org TLD. Afilias and PIR also detailed on September 26, 2008, that the first phase, involving large registrars it has a strong working relationship with ("friends and family") would be

2070-414: The operating system or via some other trusted source. When DNSSEC was originally designed, it was thought that the only trust anchor that would be needed was for the DNS root . The root anchors were first published on 15 July 2010. An authentication chain is a series of linked DS and DNSKEY records, starting with a trust anchor to the authoritative name server for the domain in question. Without

2139-472: The (fictitious) domains j.example.com and l.example.com . This is also possible with NSEC3 records. CloudFlare pioneered a pair of alternative approaches, which manage to achieve the same result in one third of the response size. The first is a variation on the "white lies" approach, called "black lies", which exploits common DNS client behavior to state the nonexistence more compactly. The second approach instead chooses to prove that "the record exists but

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2208-524: The 8-bit Intel 8080 processor of 1974. The Zilog Z80 , however, was fully backward compatible with the Intel 8080.) Fully backward compatible processors can process the same binary executable software instructions as their predecessors, allowing the use of a newer processor without having to acquire new applications or operating systems . Similarly, the success of the Wi-Fi digital communication standard

2277-559: The Checking Disabled (CD) bit in its query messages. A validating stub resolver uses the CD bit to perform its own recursive authentication. Using such a validating stub resolver gives the client end-to-end DNS security for domains implementing DNSSEC, even if the Internet service provider or the connection to them is not trusted. Non-validating stub resolvers must rely on external DNSSEC validation services, such as those controlled by

2346-553: The DNS such as Certificate Records ( CERT records , RFC   4398 ), SSH fingerprints ( SSHFP , RFC   4255 ), IPSec public keys (IPSECKEY, RFC   4025 ), TLS Trust Anchors ( TLSA , RFC   6698 ), or Encrypted Client Hello (SVCB/HTTPS records for ECH ). DNSSEC does not provide confidentiality of data; in particular, all DNSSEC responses are authenticated but not encrypted. DNSSEC does not protect against DoS attacks directly, though it indirectly provides some benefit (because signature checking allows

2415-482: The IETF RFC 2535 specification had very significant problems scaling up to the full Internet; by 2001 it became clear that this specification was unusable for large networks. In normal operation DNS servers often get out of sync with their parents. This isn't usually a problem, but when DNSSEC is enabled, this out-of-sync data could have the effect of a serious self-created denial of service. The original DNSSEC required

2484-460: The IP addresses ( A record and/or AAAA records ) of the domain "www. example.com ". There are several exceptions to the above example. First, if "example.com" does not support DNSSEC, there will be no RRSIG record in the answer and there will not be a DS record for "example.com" in the "com" zone. If there is a DS record for "example.com", but no RRSIG record in the reply, something is wrong and maybe

2553-544: The ability to more easily enumerate a zone. Due to the messy evolution of the protocol and a desire to preserve backwards compatibility, online DNSSEC signing servers return a "white lie" instead of authenticating a denial of existence directly. The technique outlined in RFC 4470 returns a NSEC record in which the pairs of domains lexically surrounding the requested domain. For example, request for k.example.com would thus result in an NSEC record proving that nothing exists between

2622-655: The basis that it would allow for easy backwards compatibility with the original Nintendo Entertainment System (NES), but ultimately did not proved to be workable once the rest of the Super NES's architecture was designed. List of DNS record types This list of DNS record types is an overview of resource records (RRs) permissible in zone files of the Domain Name System (DNS). It also contains pseudo-RRs. Other types of records simply provide some types of information (for example, an HINFO record gives

2691-437: The data is truly from or not available from the domain owner. The DNSSEC specifications (called DNSSEC-bis ) describe the current DNSSEC protocol in great detail. See RFC   4033 , RFC   4034 , and RFC   4035 . With the publication of these new RFCs (March 2005), an earlier RFC, RFC   2535 has become obsolete. The full set of RFCs that specify DNSSEC are collected in RFC   9364 , which

2760-572: The default UDP size of 512 bytes. In theory, this can be handled through multiple IP fragments, but many "middleboxes" in the field do not handle these correctly. This leads to the use of TCP instead. Yet many current TCP implementations store a great deal of data for each TCP connection; heavily loaded servers can run out of resources simply trying to respond to a larger number of (possibly bogus) DNSSEC requests. Some protocol extensions, such as TCP Cookie Transactions , have been developed to reduce this loading. To address these challenges, significant effort

2829-408: The deployment of DNSSEC resolvers, since the root trust anchor can be used to validate any DNSSEC zone that has a complete chain of trust from the root. Since the chain of trust must be traced back to a trusted root without interruption in order to validate, trust anchors must still be configured for secure zones if any of the zones above them are not secure. For example, if the zone "signed.example.org"

Domain Name System Security Extensions - Misplaced Pages Continue

2898-505: The digital signature, a DNS resolver is able to check if the information is identical (i.e. unmodified and complete) to the information published by the zone owner and served on an authoritative DNS server. While protecting IP addresses is the immediate concern for many users, DNSSEC can protect any data published in the DNS, including text records (TXT) and mail exchange records (MX), and can be used to bootstrap other security systems that publish references to cryptographic certificates stored in

2967-435: The existing old keys. Then, when it is safe to assume that the time to live values have caused the caching of old keys to have passed, these new keys can be used. Finally, when it is safe to assume that the caching of records using the old keys have expired, the old DNSKEY records can be deleted. This process is more complicated for things such as the keys to trust anchors, such as at the root, which may require an update of

3036-493: The first 360 models in 1964 and has continued to update the series ever since, with migration over the decades from 32-bit register/24-bit addresses to 64-bit registers and addresses. Intel announced the first Intel 8086 / 8088 processors in 1978, again with migrations over the decades from 16-bit to 64-bit. (The 8086/8088, in turn, were designed with easy machine-translatability of programs written for its predecessor in mind, although they were not instruction-set compatible with

3105-444: The first to be able to sign their domains, beginning "early 2009". On June 23, 2010, 13 registrars were listed as offering DNSSEC records for .ORG domains. VeriSign ran a pilot project to allow .com and .net domains to register themselves for the purpose of NSEC3 experimentation. On February 24, 2009, they announced that they would deploy DNSSEC across all their top-level domains (.com, .net, etc.) within 24 months, and on November 16 of

3174-459: The launch of new systems, as users can pull from the previous console's library of games while developers transition to the new hardware. Moreover, studies in the mid-1990s found that even consumers who never play older games after purchasing a new system consider backward compatibility a highly desirable feature, valuing the mere ability to continue to play an existing collection of games even if they choose never to do so. Backward compatibility with

3243-664: The main CPU for PS1 mode or upclocking itself to offload I/O in PS2 mode. This coprocessor was replaced with a PowerPC -based processor in later systems to serve the same functions, emulating the PS1 CPU core. Such an approach can backfire, though, as was the case of the Super Nintendo Entertainment System (Super NES). It opted for the more peculiar 65C816 CPU over the more popular 16-bit microprocessors on

3312-406: The name instead of listing them directly. Over time, advancements in hashing using GPUs and dedicated hardware meant that NSEC3 responses could be cheaply brute forced using offline dictionary attacks. NSEC5 has been proposed to allow authoritative servers to sign NSEC responses without having to keep a private key that can be used to modify the zone. Thus stealing an NSEC5KEY would only result in

3381-431: The new system. Because of this, several console manufacturers phased out backward compatibility towards the end of the console generation in order to reduce cost and briefly reinvigorate sales before the arrival of newer hardware. It is possible to bypass some of these hardware costs. For instance, earlier PlayStation 2 (PS2) systems used the core of the original PlayStation (PS1) CPU as a dual-purpose processor, either as

3450-492: The newest generation of consoles such as PlayStation 5 and Xbox Series X/S also support this feature. A large part of the success and implementation of this feature is that the hardware within newer generation consoles is both powerful and similar enough to legacy systems that older titles can be broken down and re-configured to run on the Xbox One. This program has proven incredibly popular with Xbox players and goes against

3519-489: The operating system. Keys in DNSKEY records can be used for two different things and typically different DNSKEY records are used for each. First, there are key signing keys (KSK) which are used to sign other DNSKEY records containing zone signing keys (ZSK), which are used to sign other records. Since the ZSKs are under complete control and use by one particular DNS zone , they can be switched more easily and more often. As

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3588-497: The original PlayStation (PS) software discs and peripherals is considered to have been a key selling point for the PlayStation 2 (PS2) during its early months on the market. Despite not being included at launch, Microsoft slowly incorporated backward compatibility for select titles on the Xbox One several years into its product life cycle. Players have racked up over a billion hours with backward-compatible games on Xbox, and

3657-432: The parent and children. This does mean that clients have to do a little more work when verifying keys. More specifically, verifying a DNS zone's KEY RRset requires two signature verification operations instead of the one required by RFC 2535 (there is no impact on the number of signatures verified for other types of RRsets). Most view this as a small price to pay, since it makes DNSSEC deployment more practical. The new version

3726-423: The product that may lead to longer time to market , technological hindrances, and slowing innovation; and increased expectations from users in terms of compatibility. It also introduces the risk that developers will favor developing games that are compatible with both the old and new systems, since this gives them a larger base of potential buyers, resulting in a dearth of software which uses the advanced features of

3795-424: The recent trend of studio-made remasters of classic titles, creating what some believe to be an important shift in console makers' strategies. The monetary costs of supporting old software is considered a large drawback to the usage of backward compatibility. The associated costs of backward compatibility are a larger bill of materials if hardware is required to support the legacy systems; increased complexity of

3864-594: The requested record type does not", which they call "DNS shotgun". The Internet is critical infrastructure, yet its operation depends on the fundamentally insecure DNS. Thus, there is strong incentive to secure DNS, and deploying DNSSEC is generally considered to be a critical part of that effort. For example, the U.S. National Strategy to Secure Cyberspace specifically identified the need to secure DNS. Wide-scale deployment of DNSSEC could resolve many other security problems as well, such as secure key distribution for e-mail addresses. DNSSEC deployment in large-scale networks

3933-479: The response as a "hint to find out whether the recursive name server was able to validate signatures for all of the data in the Answer and Authority sections of the response." Microsoft Windows uses a stub resolver, and Windows Server 2008 R2 and Windows 7 in particular use a non-validating but AD-bit-aware stub resolver. A validating stub resolver can also potentially perform its own signature validation by setting

4002-442: The root domain from Algorithm 8 to Algorithm 13 is currently in planning as of early 2024. DNS-based Authentication of Named Entities (DANE) is an IETF working group with the goal of developing protocols and techniques that allow Internet applications to establish cryptographically secured communications with TLS , DTLS , SMTP , and S/MIME based on DNSSEC. The new protocols will enable additional assurances and constraints for

4071-405: The same "tag" and many signatures corresponding to that "tag" in a packet, the researchers can slow down a resolver by a factor of 2 million. In response, resolvers began to place limits on the amount of verification errors, key tag collisions, and hash calculations. Cryptographically proving the absence of a domain requires signing the response to every query for a non-existent domain. This is not

4140-422: The same year, they said the .com and .net domains would be signed by the first quarter of 2011, after delays caused by technical aspects of the implementation. This goal was achieved on-schedule and Verisign's DNSSEC VP, Matt Larson, won InfoWorld's Technology Leadership Award for 2011 for his role in advancing DNSSEC. DNSSEC was first deployed at the root level on July 15, 2010. This is expected to greatly simplify

4209-518: The security algorithms that are or were most often used: From the results of a DNS lookup, a security-aware DNS resolver can determine whether the authoritative name server for the domain being queried supports DNSSEC, whether the answer it receives is secure, and whether there is some sort of error. The lookup procedure is different for recursive name servers such as those of many ISPs , and for stub resolvers such as those included by default in mainstream operating systems. Microsoft Windows uses

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4278-403: The signatures in all of its children). Thus, DNSSEC as defined in RFC 2535 could not scale up to the Internet. The IETF fundamentally modified DNSSEC, which is called DNSSEC-bis when necessary to distinguish it from the original DNSSEC approach of RFC 2535. This new version uses "delegation signer (DS) resource records" to provide an additional level of indirection at delegation points between

4347-495: The traditional model based on public key infrastructure . They will also enable domain holders to assert certificates for themselves, without reference to third-party certificate authorities . Support for DNSSEC stapled certificates was enabled in Google Chrome 14, but was later removed. For Mozilla Firefox , support was provided by an add-on while native support is currently awaiting someone to start working on it. DNS

4416-433: The use of potentially untrustworthy parties). Other standards (not DNSSEC) are used to secure bulk data (such as a DNS zone transfer ) sent between DNS servers. As documented in RFC   4367 , some users and developers make false assumptions about DNS names, such as assuming that a company's common name plus ".com" is always its domain name. DNSSEC cannot protect against false assumptions; it can only authenticate that

4485-416: The user's Internet service provider or a public recursive name server , and the communication channels between itself and those name servers, using methods such as DNS over TLS . To be able to prove that a DNS answer is correct, one needs to know at least one key or DS record that is correct from sources other than the DNS. These starting points are known as trust anchors and are typically obtained with

4554-424: The value of supporting older software. The cultural impact of video games is a large part of their continued success, and some believe ignoring backward compatibility would cause these titles to disappear. Backward compatibility also acts as a selling point for new hardware, as an existing player base can more affordably upgrade to subsequent generations of a console. This also helps to make up for lack of titles at

4623-405: Was achieved by sending the sum of both left and right audio channels in one signal and the difference in another signal. That allows mono FM receivers to receive and decode the sum signal while ignoring the difference signal, which is necessary only for separating the audio channels. Stereo FM receivers can receive a mono signal and decode it without the need for a second signal, and they can separate

4692-420: Was secured but the "example.org" zone was not, then, even though the ".org" zone and the root are signed, a trust anchor has to be deployed in order to validate the zone. Political issues surrounding signing the root have been a continuous concern, primarily about some central issues: Backward compatibility In telecommunications and computing , backward compatibility (or backwards compatibility )

4761-490: Was to create NSEC records for every pair of domains in a zone. Thus if a client queried for a record at the non-existent k.example.com , the server would respond with an NSEC record stating that nothing exists between a.example.com and z.example.com . However, this leaks more information about the zone than traditional unauthenticated NXDOMAIN errors because it exposes the existence of real domains. The NSEC3 records (RFC 5155) were created as an alternative which hashes

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