(12) Patent Application Publication (10) Pub. No.: US 2010/0011420 A1 DRAKO Et Al

US 2010.0011420A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2010/0011420 A1 DRAKO et al. (43) Pub. Date: Jan. 14, 2010 (54) OPERATING ASERVICE ON ANETWORKAS (22) Filed: Jul. 2, 2008 ADOMAN NAME SYSTEM SERVER Publication Classification (75) Inventors: DEAN DRAKO, Los Altos, CA (51) Int. Cl. (US); Zachary Levow, Mountain G06F 7/30 (2006.01) View, CA (US) G06F 5/16 (2006.01) Correspondence Address: H04L 9/32 (2006.01) PATENTRY (52) U.S. Cl. ................. 726/5: 709/245; 707/3; 709/206; P.O. BOX 151616 709/201: 707/E17.014; 707/E17.115; 707/E17.032 SAN RAFAEL, CA 94.915-1616 (US) (57) ABSTRACT (73) Assignee: BARRACUDANETWORKS INC., CAMPBELL, CA (US) Operating a service Such as a remote database as a dins server, receiving inputs such as queries as domain names and trans (21) Appl. No.: 12/167,134 mitting replies in the format of IPv4 or IPv6 addresses. IP CONNECT EMAIL HEADER PARAMETERS FORMING FODN AUTHCODE. IPADDRESS. DNS HERARCHY CLIENT.DB SYSTEM DNS DNS RESOLVER SERVER 20 30 DATABASE 140 Patent Application Publication Jan. 14, 2010 Sheet 1 of 4 US 2010/0011420 A1 IP CONNECT EMAIL HEADER PARAMETERS FORMING FODN AUTHCODE. IPADDRESS. DNS HERARCHY CLIENT.DB SYSTEM DNS DNS RESOLVER SERVER 20 30 DATABASE 40 FIG. Patent Application Publication Jan. 14, 2010 Sheet 2 of 4 US 2010/0011420 A1 IP CONNECT EMAIL HEADER PARAMETERS FORMING FODN AUTHCODE. IPADDRESS. DNS HERARCHY CLIENT.DB SYSTEM DNS FODN DNS DNS OUERY 121 RESOLVER SERVER 20 30 DATABASE 40 FIG.2 Patent Application Publication Jan. 14, 2010 Sheet 3 of 4 US 2010/0011420 A1 DNS HERARCHY SYSTEM DNS DNS RESOLVER SERVER 2O DATABASE ANALYZE 40 BYPASS FIG.3 Patent Application Publication Jan. 14, 2010 Sheet 4 of 4 US 2010/0011420 A1 IP CONNECT EMAIL HEADER PARAMETERS FORMING FODN AUTHCODE. IPADDRESS. DNS HERARCHY CLIENT.DB SYSTEM DNS FODN DNS DNS OUERY 121 RESOLVER SERVER 2O DATABASE ANALYZE 40 BYPASS FIG.4 US 2010/001. 1420 A1 Jan. 14, 2010 OPERATING ASERVICE ON ANETWORKAS DOMAIN NAMES SYSTEM BACKGROUND A DOMAN NAME SYSTEM SERVER 0007. A domain name usually consists of two or more parts (technically labels), separated by dots. For example: CO-PENDING APPLICATIONS example.com. 0008. The rightmost label conveys the top-level domain 0001. Three related applications with common inventors (for example, the address www.example.com has the and assignee are/will be pending: querying a database as a dins top-level domain com). client, operating a service e.g. database as a dins server, and 0009. Each label to the left specifies a subdivision, or facilitating email by checking a database with email coordi subdomain of the domain above it. Note:"subdomain' nates. expresses relative dependence, not absolute depen 0002 Docket Number application numbers: file dates: dence. For example: example.com comprises a Subdo main of the com domain, and www.example.com com 0003) Z-PTNTR200808 prises a Subdomain of the domain example.com. In 0004 Z-PTNTR200809 theory, this subdivision can go down to 127 levels deep. 0005 Z-PTNTR200810 Each label can contain up to 63 characters. The whole domain name does not exceed a total length of 255 TECHNICAL FIELD characters. In practice, Some domain registries may have shorter limits. 0006. The field of the invention is internet based informa 0010. A hostname refers to a domain name that has one tion technology operations and an application to facilitating or more associated IP addresses; ie: the www.example. the transmission of email. com’ and example.com domains are both hostnames, however, the “com domain is not. O011 DNS Servers 0012. The Domain Name System consists of a hierarchical Definition List 1 set of DNS servers. Each domain or subdomain has one or more authoritative DNS servers that publish information Term Definition about that domain and the name servers of any domains Email parameter A text string which is either part of an “beneath” it. The hierarchy of authoritative DNS servers argument of a mail protocol command or a component of a TCP packet header matches the hierarchy of domains. At the top of the hierarchy connecting between email servers. Not stand the root nameservers: the servers to query when looking limited to but includes IP addresses and up (resolving) a top-level domain name (TLD). domain names. The present application 0013 Users generally do not communicate directly with defines and uses this term. IP address An internet protocol (IP) address is DNS. Instead DNS-resolution takes place transparently in e.g. 151.207.245.67 defined in RFC-791 IPv4 standard of the client-applications such as web-browsers, mail-clients, and Internet Engineering Task Force. RFC other Internet applications. When an application makes a 791 defines a replacement IPv6. request which requires a DNS lookup, Such programs send a Domain name Defined in RFC-1034, 1035, 1085, a e.g. www.uspto.gov domain name is a memorable host name resolution request to the local DNS resolver in the local that stands in for a numeric IP address. operating system, which in turn handles the communications DNS Domain Name System defined in RFC required. 1035, includes resolvers and servers 0014. The DNS resolver likely has a cache containing which respond to questions about domain names. The most basic task of recent lookups. If the cache can provide the answer to the DNS is to translate hostnames to IP request, the resolver will return the value in the cache to the addresses. The Domain Name System program that made the request. If the cache does not contain consists of a hierarchical set of DNS the answer, the resolver will send the request to one or more SeWes. SMTP Simple Mail Transfer Protocol designated DNS servers. documented in RFC 2821 0015. When a DNS client needs to look up a name used in DNSBL DNSBL is an abbreviation that usually a program, it queries DNS servers to resolve the name. Each stands for DNS blacklist. Typically query message the client sends contains three pieces of infor entails a domain, a nameserver for that domain, and a list of addresses to mation, specifying a question for the server to answer: publish. Generally returns either an 0016 A specified DNS domain name, stated as a fully address, indicating that the client is qualified domain name (FQDN) listed; or an “NXDOMAIN” (“No such 0.017. A specified query type, which can either specify a domain') code. DNSBL provides resources to support blocking spam. resource record by type or a specialized type of query Fully qualified A fully qualified domain name has at operation. domain name least a host and domain name, including 0.018. A specified class for the DNS domain name. top-level domain. (0019 For example, the name specified could be the FQDN A FQDN always starts with a host name and continues all the way up to the top for a computer, Such as "host—a.example.com., and the level domain name and includes query type specified to look for an address (A) resource intermediate level domains to provide an record by that name. Think of a DNS query as a client asking unambiguous path which specifies the exact location of a host in the Domain a question, Such as "Do you have any A resource records for Name System's tree hierarchy through to a computer named hostname.example.com.?' When the cli a top-level domain ent receives an answer from the server, it reads and interprets the answered A resource record, learning the IP address for the computer it asked for by name. US 2010/001. 1420 A1 Jan. 14, 2010 0020 DNS queries resolve in a number of different ways. deliver e-mail for a particular address. The domain to mail A client can sometimes answer a query locally using cached exchanger mapping provided by DNS MX records tells where information obtained from a previous query. The DNS server to deliver email for a domain. can use its own cache of resource record information to 0034 Sender Policy Framework and DomainKeys instead answer a query. A DNS server can also query or contact other of creating their own record types were designed to take DNS servers on behalf of the requesting client to fully resolve advantage of another DNS record type, the TXT record. In the name, then sendananswer back to the client. This process these cases the TXT record contains a policy or a public key. is known as recursion. 0035. Protocol Details 0021. In addition, the client itself can attempt to contact 0036 DNS primarily uses UDP on port 53 to serve additional DNS servers to resolve a name. In general, the requests. Almost all DNS queries consist of a single UDP DNS query process occurs in two parts: request from the client followed by a single UDP reply from 0022. A name query begins at a client computer and is the server. TCP comes into play only when the response data query beg p size exceeds 512 bytes, or for Such tasks as Zone transfer. passed to a resolver, the DNSClient service, for resolution. Some operating systems such as HP-UX are known to have 0023. When the query cannot be resolved locally, DNS resolver implementations that use TCP for all queries, even servers can be queried as needed to resolve the name. when UDP would suffice. 0024. In the initial steps of the query process, a DNS 0037 Important categories of data stored in DNS include domain name is used in a program on the local computer.

Load more