Custom DNS Readme

Important information to know about Custom DNS

Alternate Port Redirection

If your ISP blocks port 80, you can use the WebHop feature to redirect your Custom DNS hosts to your server on alternate ports using our webhop URL forwarding engine. If your ISP blocks port 25, you can use our MailHop Relay and MailHop Outbound services to redirect your mail around the blocked port.

Available Record Types

The Custom DNS service supports A, CNAME, MX, and TXT records in the Standard interface, and includes AAAA, LOC, NS, PTR and SRV in the Expert interface. You can learn more about the Standard interface and record types here, and learn more about the Expert interface and record types here.

Available TLDs

Custom DNS supports nearly all of the top-level domains available to the ICANN root servers, including all global top-level domains (gTLD) such as .com, .edu, .gov, .org, .net; sponsored TLDs such as .aero, .biz, .coop, .info, .name, .pro; and nearly all of the country code TLDs (ccTLDs), including (but not limited to) the following:

.ac, .ae, .ag, .ar, .as, .at, .au, .aw, .bb, .be, .bg, .bm, .bo, .br, .by, .bz, .ca, .cat, .cc, .cd, .ch, .cl, .cn, .co, .cr, .cx, .cz, .de, .dj, .do, .ec, .ee, .es, .eu, .fi, .fm, .fr, .gg, .gi, .gl, .gr, .gs, .gt, .hk, .hm, .hr, .ht, .hu, .id, .ie, .il, .im, .is, .it, .je, .jp, .kr, .ky, .la, .li, .lk, .lt, .lu, .lv, .md, .mo, .ms, .mt, .mu, .mx, .my, .no, .nr, .nu, .nz, .pa, .pe, .ph, .pk, .pl, .pt, .ro, .ru, .sa, .se, .sg, .sh, .si, .sk, .st, .tc, .th, .tk, .to, .tr, .tv, .tw, .uk, .us, .uy, .uz, .vc, .ve, .vg, .vn, .vu, .ws, .za

Unfortunately, some TLDs are difficult or impossible to use with our services. For example, .nl and .dk have policies at their registries which prevent them from delegating domains to our servers, and many .de registrars have difficulty as well. Alternate roots such as .geek, .parody, and .scifi are currently unsupported, nor would they function with significant portions of the internet even if we supported them.

Please note: Our supported TLDs in Custom DNS is far larger than the list of domains we offer for registration. Please see our list of available TLDs for registration. You can use Custom DNS for your domain without transferring the domain to us by delegating the domain to our nameservers.

Custom DNS Nameservers

Please see our How-to for the full list of our Custom DNS nameservers and their IP addresses.

Pre-activation

Some TLDs require that a DNS provider's nameservers be pre-activated before a domain can be delegated to them. Pre-activation also allows customers to query our nameservers for their records prior to delegation so they can double-check their configuration. If you would like your Custom DNS zone pre-activated, please contact our support team to request the pre-activation. Pre-activation can take up to two hours to complete, and the Custom DNS zone cannot be modified until the activation is completed. We also pre-activate the following TLDs automatically: at, au, br, ch, cx, de, fi, fr, hu, ie, is, it, li, lu, mx, nl, no, nu, nz, pt, ru, se, si, tz, uk, za

Offline Hostname

The Offline Hostname feature temporarily sets a host to our offline webpage to provide helpful error messages to your visitors. This feature is useful for maintenance windows, outages, and other times when your server isn't available for a short while and you need to let your visitors know without setting up a second server and temporary downtime page elsewhere. The Offline Hostname feature is not failover (automated detection and redirection for unavailable servers); if you do need failover service, you may be interested in our Dynect services.

Reverse DNS

Please see our Reverse DNS in Custom DNS article for more information. In general, your ISP should be able to create the necessary PTR records on their end to provide reverse DNS for your domain. You will need a static IP address to have reverse DNS created for you. If you have a dynamic IP address, your ISP refuses to create the necessary records, and/or your ISP refuses to delegate the address to us, you can use our MailHop Outbound service to prevent anti-spam rejections for lacking reverse DNS resolution.

Round Robin Records

Round Robin A records in DNS is intended to evenly distribute queries between each host of the same name. Here is an example zone with four Round Robin records:

Host		TTL	Type	Data
a.domain.com	60	A	1.1.1.1
a.domain.com	60	A	2.2.2.2
a.domain.com	60	A	3.3.3.3
a.domain.com	60	A	4.4.4.4

Theoretically, each of these records will be returned to a visitor in sequence; for any given number of queries, each record should be returned exactly 25% of the time. However, this is not always the case. For example, Microsoft Windows has a tendency to sort the record list received and choose the same two or three every time, regardless of the number of records available; furthermore, Windows ignores records after the first 13, if more than 13 are provided.

Additionally, Round Robin is not intended as a form of DNS failover. Unlike MX records, which have Preference values and priority, Round Robin host records simply return the records in sequential order. If the services at one of the IP addresses fails, queries will still receive the address of the unavailable host; in the above example, this would mean 25% of visitors to 'a.domain.com' would reach an inaccessible server.

Last, Round Robin host records cannot be updated via our update API and update clients. Therefore, it is not possible to use dynamic IP addresses with Round Robin unless you manually edit the list each time a change must be made.

Round Robin does have its uses, but "smart" load balancing and automatic failover are not part of it. If your domain does require load balancing and automatic failover, please see our Dynect service for these features and many more.

Third-Party DNS

To preserve the integrity of our Custom DNS service, we do not allow transfers from our nameservers to any third party. If your domain delegation includes any "foreign" nameservers, the Custom DNS service will deactivate within two weeks of the change, or fail to initially activate until the extraneous nameservers are removed.

If you wish to host your own primary DNS and use other companies, including DynDNS, as secondary providers for the domain, please see our Secondary DNS service. Secondar DNS will function if other DNS providers are listed in the delegation, though it will still refuse transfer requests to these servers.

Wildcard A and CNAME Records

Wildcard A or CNAME records resolve any hostnames at or below a given level. Here is an example zone with three normal host records and a Wildcard:

Host		TTL	Type	Data
a.domain.com	60	A	1.1.1.1
b.domain.com	60	A	2.2.2.2
c.domain.com	60	A	3.3.3.3
*.domain.com	60	A	4.4.4.4

Visitors to a.domain.com, b.domain.com, and c.domain.com will receive the IP addresses 1.1.1.1, 2.2.2.2 and 3.3.3.3, respectively. However, thanks to the Wildcard host, any other third-level hostname will receive the IP address 4.4.4.4, including www.domain.com, d.domain.com, qwerty.domain.com, asdf1234.domain.com, this.is.a.host.record.domain.com and so on. Wildcard records are particularly useful for virtual hosting.