DNSreport for amazon.com
Email link to resultsGenerated by www.DNSreport.com at 18:04:23 GMT on 05 May 2009.
| Category | Status | Test Name | Information |
|---|---|---|---|
| Parent | PASS | Missing Direct Parent check | OK. Your direct parent zone exists, which is good. Some domains (usually third or fourth level domains, such as example.co.us) do not have a direct parent zone ('co.us' in this example), which is legal but can cause confusion. |
| INFO | NS records at parent servers | Your NS records at the parent servers are:udns1.ultradns.net. [204.69.234.1] [TTL=172800] [US][These were obtained from k.gtld-servers.net] | |
| PASS | Parent nameservers have your nameservers listed | OK. When someone uses DNS to look up your domain, the first step (if it doesn't already know about your domain) is to go to the parent servers. If you aren't listed there, you can't be found. But you are listed there. | |
| PASS | Glue at parent nameservers | OK. The parent servers have glue for your nameservers. That means they send out the IP address of your nameservers, as well as their host names. | |
| PASS | DNS servers have A records | OK. All your DNS servers either have A records at the zone parent servers, or do not need them (if the DNS servers are on other TLDs). A records are required for your hostnames to ensure that other DNS servers can reach your DNS servers. Note that there will be problems if your DNS servers do not have these same A records. |
| NS | INFO | NS records at your nameservers | Your NS records at your nameservers are:pdns5.ultradns.info. [204.74.114.1] [TTL=86400]
|
| PASS | Open DNS servers | OK. Your DNS servers do not announce that they are open DNS servers. Although there is a slight chance that they really are open DNS servers, this is very unlikely. Open DNS servers increase the chances that of cache poisoning, can degrade performance of your DNS, and can cause your DNS servers to be used in an attack (so it is good that your DNS servers do not appear to be open DNS servers). | |
| PASS | Mismatched glue | OK. The DNS report did not detect any discrepancies between the glue provided by the parent servers and that provided by your authoritative DNS servers. | |
| PASS | No NS A records at nameservers | OK. Your nameservers do include corresponding A records when asked for your NS records. This ensures that your DNS servers know the A records corresponding to all your NS records. | |
| PASS | All nameservers report identical NS records | OK. The NS records at all your nameservers are identical. | |
| PASS | All nameservers respond | OK. All of your nameservers listed at the parent nameservers responded. | |
| PASS | Nameserver name validity | OK. All of the NS records that your nameservers report seem valid (no IPs or partial domain names). | |
| PASS | Number of nameservers | OK. You have 2 nameservers. You must have at least 2 nameservers (RFC2182 section 5 recommends at least 3 nameservers), and preferably no more than 7. | |
| PASS | Lame nameservers | OK. All the nameservers listed at the parent servers answer authoritatively for your domain. | |
| FAIL | Missing (stealth) nameservers | FAIL:
You have one or more missing (stealth) nameservers. The following
nameserver(s) are listed (at your nameservers) as nameservers for your
domain, but are not listed at the parent nameservers (therefore, they
may or may not get used, depending on whether your DNS servers return
them in the authority section for other requests, per RFC2181
5.4.1). You need to make sure that these stealth nameservers are
working; if they are not responding, you may have serious problems! The
DNSreport will not query these servers, so you need to be very careful
that they are working properly.pdns5.ultradns.info.This
is listed as an ERROR because there are some cases where nasty problems
can occur (if the TTLs vary from the NS records at the root servers and
the NS records point to your own domain, for example).
| |
| FAIL | Missing nameservers 2 | ERROR:
One or more of the nameservers listed at the parent servers are not
listed as NS records at your nameservers. The problem NS records are: udns1.ultradns.net. udns2.ultradns.net. | |
| PASS | No CNAMEs for domain | OK. There are no CNAMEs for amazon.com. RFC1912 2.4 and RFC2181 10.3 state that there should be no CNAMEs if an NS (or any other) record is present. | |
| PASS | No NSs with CNAMEs | OK. There are no CNAMEs for your NS records. RFC1912 2.4 and RFC2181 10.3 state that there should be no CNAMEs if an NS (or any other) record is present. | |
| PASS | Nameservers on separate class C's | OK. You have nameservers on different Class C (technically, /24) IP ranges. You must have nameservers at geographically and topologically dispersed locations. RFC2182 3.1 goes into more detail about secondary nameserver location. | |
| PASS | All NS IPs public | OK. All of your NS records appear to use public IPs. If there were any private IPs, they would not be reachable, causing DNS delays. | |
| PASS | TCP Allowed | OK. All your DNS servers allow TCP connections. Although rarely used, TCP connections are occasionally used instead of UDP connections. When firewalls block the TCP DNS connections, it can cause hard-to-diagnose problems. | |
| INFO | Nameservers versions | [For security reasons, this test is restricted to customers.] | |
| FAIL | Stealth NS record leakage | Your DNS servers leak stealth information in non-NS requests: Stealth nameservers are leaked [pdns6.ultradns.co.uk.]! Stealth nameservers are leaked [pdns5.ultradns.info.]! Stealth nameservers are leaked [pdns4.ultradns.org.]! Stealth nameservers are leaked [pdns3.ultradns.org.]! Stealth nameservers are leaked [pdns2.ultradns.net.]! Stealth nameservers are leaked [pdns1.ultradns.net.]! This can cause some serious problems (especially if there is a TTL discrepancy). If you must have stealth NS records (NS records listed at the authoritative DNS servers, but not the parent DNS servers), you should make sure that your DNS server does not leak the stealth NS records in response to other queries. |
| SOA | INFO | SOA record | Your SOA record [TTL=7200] is:Primary nameserver: udns1.ultradns.net.
|
| PASS | NS agreement on SOA Serial # | OK.
All your nameservers agree that your SOA serial number is 2009050102.
That means that all your nameservers are using the same data (unless
you have different sets of data with the same serial number, which
would be very bad)! Note that the DNSreport only checks the NS records
listed at the parent servers (not any stealth servers). | |
| PASS | SOA MNAME Check | OK. Your SOA (Start of Authority) record states that your master (primary) name server is: udns1.ultradns.net.. That server is listed at the parent servers, which is correct.
| |
| PASS | SOA RNAME Check | OK. Your SOA (Start of Authority) record states that your DNS contact E-mail address is: hostmaster@amazon.com. (techie note: we have changed the initial '.' to an '@' for display purposes). | |
| PASS | SOA Serial Number | OK. Your SOA serial number is: 2009050102. This appears to be in the recommended format of YYYYMMDDnn, where 'nn' is the revision. So this indicates that your DNS was last updated on 01 May 2009 (and was revision #2). This number must be incremented every time you make a DNS change. | |
| PASS | SOA REFRESH value | OK. Your SOA REFRESH interval is : 28800 seconds. This seems normal (about 3600-7200 seconds is good if not using DNS NOTIFY; RFC1912 2.2 recommends a value between 1200 to 43200 seconds (20 minutes to 12 hours)). This value determines how often secondary/slave nameservers check with the master for updates. | |
| PASS | SOA RETRY value | OK. Your SOA RETRY interval is : 3600 seconds. This seems normal (about 120-7200 seconds is good). The retry value is the amount of time your secondary/slave nameservers will wait to contact the master nameserver again if the last attempt failed. | |
| PASS | SOA EXPIRE value | OK. Your SOA EXPIRE time: 1209600 seconds. This seems normal (about 1209600 to 2419200 seconds (2-4 weeks) is good). RFC1912 suggests 2-4 weeks. This is how long a secondary/slave nameserver will wait before considering its DNS data stale if it can't reach the primary nameserver. | |
| PASS | SOA MINIMUM TTL value | OK. Your SOA MINIMUM TTL is: 3600 seconds. This seems normal (about 3,600 to 86400 seconds or 1-24 hours is good). RFC2308 suggests a value of 1-3 hours. This value used to determine the default (technically, minimum) TTL (time-to-live) for DNS entries, but now is used for negative caching. |
| MX | INFO | MX Record | Your 3 MX records are:10 smtp-fw-9101.amazon.com. [TTL=7200] IP=207.171.184.25 [TTL=7200] [US] |
| PASS | Low port test | OK. Our local DNS server that uses a low port number can get your MX record. Some DNS servers are behind firewalls that block low port numbers. This does not guarantee that your DNS server does not block low ports (this specific lookup must be cached), but is a good indication that it does not. | |
| PASS | Invalid characters | OK. All of your MX records appear to use valid hostnames, without any invalid characters. | |
| PASS | All MX IPs public | OK. All of your MX records appear to use public IPs. If there were any private IPs, they would not be reachable, causing slight mail delays, extra resource usage, and possibly bounced mail. | |
| PASS | MX records are not CNAMEs | OK. Looking up your MX record did not just return a CNAME. If an MX record query returns a CNAME, extra processing is required, and some mail servers may not be able to handle it. | |
| PASS | MX A lookups have no CNAMEs | OK. There appear to be no CNAMEs returned for A records lookups from your MX records (CNAMEs are prohibited in MX records, according to RFC974, RFC1034 3.6.2, RFC1912 2.4, and RFC2181 10.3). | |
| PASS | MX is host name, not IP | OK. All of your MX records are host names (as opposed to IP addresses, which are not allowed in MX records). | |
| PASS | Multiple MX records | OK. You have multiple MX records. This means that if one is down or unreachable, the other(s) will be able to accept mail for you. | |
| PASS | Differing MX-A records | OK. I did not detect differing IPs for your MX records (this would happen if your DNS servers return different IPs than the DNS servers that are authoritative for the hostname in your MX records). | |
| PASS | Duplicate MX records | OK. You do not have any duplicate MX records (pointing to the same IP). Although technically valid, duplicate MX records can cause a lot of confusion, and waste resources. | |
| PASS | Reverse DNS entries for MX records | OK. The IPs of all of your mail server(s) have reverse DNS (PTR) entries. RFC1912
2.1 says you should have a reverse DNS for all your mail servers. It is
strongly urged that you have them, as many mailservers will not accept
mail from mailservers with no reverse DNS entry. Note that this
information is cached, so if you changed it recently, it will not be reflected here (see the www.DNSstuff.com Reverse DNS Tool for the current data). The reverse DNS entries are:
25.184.171.207.in-addr.arpa smtp-fw-9101.amazon.com. [TTL=769]
|
| PASS | Connect to mail servers | OK: I was able to connect to all of your mailservers. | |
| PASS | Mail server host name in greeting | OK: All of your mailservers have their host name in the greeting:smtp-fw-4101.amazon.com:<br /> 220 smtp-fw-4101.amazon.com ESMTP
<br />smtp-fw-2101.amazon.com:<br /> 220 smtp-fw-2101.amazon.com ESMTP
<br />smtp-fw-9101.amazon.com:<br /> 220 smtp-fw-9101.amazon.com ESMTP
<br /> | |
| PASS | Acceptance of NULL <> sender | OK: All of your mailservers accept mail from "<>". You are required (RFC1123 5.2.9) to receive this type of mail (which includes reject/bounce messages and return receipts). | |
| PASS | Acceptance of postmaster address | OK: All of your mailservers accept mail to postmaster@amazon.com (as required by RFC822 6.3, RFC1123 5.2.7, and RFC2821 4.5.1). | |
| PASS | Acceptance of abuse address | OK: All of your mailservers accept mail to abuse@amazon.com. | |
| INFO | Acceptance of domain literals | WARNING:
One or more of your mailservers does not accept mail in the domain
literal format (user@[0.0.0.0]). Mailservers are technically required RFC1123
5.2.17 to accept mail to domain literals for any of its IP addresses.
Not accepting domain literals can make it more difficult to test your
mailserver, and can prevent you from receiving E-mail from people
reporting problems with your mailserver. However, it is unlikely that
any problems will occur if the domain literals are not accepted
(mailservers at many common large domains have this problem).smtp-fw-4101.amazon.com's postmaster@[72.21.198.25] response:<br />
>>> RCPT TO:<postmaster@[72.21.198.25]><br />
<<< 550 #5.1.0 Address rejected.
<br />
smtp-fw-2101.amazon.com's postmaster@[72.21.196.25] response:<br />
>>> RCPT TO:<postmaster@[72.21.196.25]><br />
<<< 550 #5.1.0 Address rejected.
<br />
smtp-fw-9101.amazon.com's postmaster@[207.171.184.25] response:<br />
>>> RCPT TO:<postmaster@[207.171.184.25]><br />
<<< 550 #5.1.0 Address rejected.
<br />
| |
| PASS | Open relay test | OK: All of your mailservers appear to be closed to relaying. This is not a thorough check, you can get a thorough one here.smtp-fw-4101.amazon.com OK: 550 #5.1.0 Address rejected.
<br />smtp-fw-2101.amazon.com OK: 550 #5.1.0 Address rejected.
<br />smtp-fw-9101.amazon.com OK: 550 #5.1.0 Address rejected.
<br /> | |
| PASS | SPF record | You have an SPF record.
This is very good, as it will help prevent spammers from abusing your
domain. Your SPF record (I don't check to see if it is well designed!)
is: |
| WWW | INFO | WWW Record | You have one or more A records for www.amazon.com. I can't test further, however, since www.amazon.com is in its own zone. |
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